Secretary of State Marco Rubio arrived on Monday in Saudi Arabia for the second leg of a whistle-stop Middle East tour to discuss the future of both Gaza and Ukraine. The visit came amid criticism that the Trump administration was acting without consulting relevant foreign partners about the wars in both countries.

The Saudi embassy in Washington announced that Mr. Rubio met with Faisal bin Farhan, the Saudi foreign minister, while a meeting with Crown Prince Mohammed bin Salman was expected later in the day.

Mr. Rubio, who flew to Riyadh from Israel, was expected to press the Saudi leadership to propose a vision for postwar Gaza. President Trump’s idea to depopulate and occupy the territory has spurred widespread opposition in the Arab world, including in Saudi Arabia. That has led Mr. Rubio and other U.S. officials to encourage Arab leaders to suggest an alternative.

Mr. Rubio is also scheduled to meet in Riyadh on Tuesday with Russian officials to discuss the future of the Russia-Ukraine war. They will be joined by two other key U.S. officials — Mike Waltz, the national security adviser, and Steve Witkoff, Mr. Trump’s Middle East envoy, who also works on Ukraine-Russia issues — according to Tammy Bruce, a State Department spokeswoman.

In addition to angering Arab allies with his contentious proposal for Gaza, Mr. Trump frustrated partners in Europe when he spoke last week unilaterally with President Vladimir V. Putin of Russia about Ukraine’s future. His administration has also said that European governments will play no role in future talks, despite the conflict taking place within Europe’s borders.

The moves prompted concern in Ukraine and elsewhere in Europe, where leaders fear being sidelined from discussions that will dictate their countries’ futures. Volodymyr Zelensky, the Ukrainian president, reiterated in an interview that aired on Sunday that his country would “never” accept a peace deal struck by the United States and Russia if Ukraine was not involved in the talks.

Mr. Rubio’s visit comes amid swirling uncertainty about the future of the cease-fire between Israel and Hamas in Gaza, as well as the long-term governance of the territory.

Israeli officials were expected to meet in Cairo on Monday to iron out disagreements about sending humanitarian aid, including temporary accommodation, to Gaza. But the Israeli government has yet to decide whether to advance negotiations to extend the truce, which will lapse in early March unless Hamas and Israel restart talks. Israeli cabinet ministers were set to gather on Monday evening to debate the issue, but it was not certain that they would vote on it.

The Israeli leadership wants to avoid prolonging the truce if it allows Hamas to survive the war as a military force. But Hamas, though indicating a willingness to share administrative control of the territory, appears unwilling to disarm its military wing.

Mr. Trump has suggested ending the impasse by depopulating Gaza and sending its residents to Egypt and Jordan — a move strongly opposed by those countries as well as Saudi Arabia. The forced expulsion of Palestinians would be ethnic cleansing and a war crime, international law experts say.

The Trump administration’s proposal has created a further obstacle to Israel’s long-sought goal of normalizing diplomatic ties with Saudi Arabia. The Saudi leadership has said that it will not recognize Israel if Palestinians are displaced from Gaza, or if Israel refuses to create a pathway to Palestinian sovereignty.

The discussion grew more fraught after Benjamin Netanyahu, the Israeli prime minister, suggested that Saudi Arabia host Palestinian refugees and create a Palestinian state on Saudi soil.

Saudi Arabia’s Foreign Ministry rejected Mr. Netanyahu’s statements as those of “an extremist, occupying mind-set” that fails to understand the historical and cultural significance of Palestinian land.

Here’s what else is happening in the region:

• The Israeli military said on Monday that it had killed a senior Hamas operative, Muhammad Shaheen, in a strike in Lebanon. Hamas has long maintained a presence in Lebanon and has often acted there in coordination with its Lebanese ally, Hezbollah. The strike came a day before a cease-fire in Lebanon between Israel and Hezbollah is set to elapse. Officials hope to extend the truce, even though Israel is expected to keep troops in several positions inside the Lebanese border past the deadline.

Gabby Sobelman contributed reporting from Rehovot, Israel.

The leaders of many of Europe’s biggest countries on Monday will descend on Paris in an effort to forge a strategy for their own security as President Trump’s envoys prepared for talks with Russia over ending the war in Ukraine without them.

The meeting in Paris was pulled together rapidly, after Vice President JD Vance’s scathing speech in Munich criticizing Europe’s exclusion of far-right groups from power and the fast-emerging American plans to begin peace talks with Russia in Saudi Arabia this week, without the presence of Ukrainian or European leaders.

Expected in Paris are leaders from Germany, Britain, Italy, Poland, Spain, the Netherlands and Denmark, as well as the president of the European Council, the president of the European Commission and the secretary general of NATO.

On their agenda: what Europeans are willing to commit to secure any peace deal over the war in Ukraine in the short term, and in the long term, to secure the continent as it faces an aggressive, expansionist Russia and the predicted withdrawal of the assurance of American support.

The informal meeting was arranged by President Emmanuel Macron of France, who has made calls for increased European sovereignty and capacity for self-defense a hallmark of his presidency. It is expected to be the first of many such meetings between European leaders in the coming weeks, an adviser to Mr. Macron said.

“Europeans must do more, do better and work in a coherent manner towards our collective security,” the adviser, who insisted on anonymity in line with French political practice, said Sunday night.

The leaders are expected to talk about what forms European contributions to a peacekeeping force in Ukraine might take, including delivering weapons to Ukraine and the possible deployment of troops.

On Sunday, Prime Minister Keir Starmer of Britain said in an article published in The Daily Telegraph that he was “ready and willing to contribute to security guarantees to Ukraine by putting our own troops on the ground if necessary.”

“Securing a lasting peace in Ukraine that safeguards its sovereignty for the long term is essential if we are to deter Putin from further aggression in the future,” Mr. Starmer wrote, referring to President Vladimir V. Putin of Russia.

Mr. Macron has been speaking for months to European leaders about forming a cease-fire buffer force in Ukraine to ensure that any peace deal with Russia is maintained.

European leaders are also expected to discuss the acceleration of European defense capabilities, as many now believe that the United States will withdraw tens of thousands of American troops from Europe.

Just 23 of 32 NATO members now spend at least 2 percent of GDP on defense — more than a decade after vowing to do so in 2014. And NATO has made it clear that 2 percent must be “a floor not a ceiling,” and more must be spent.

The meeting comes the same day that Secretary of State Marco Rubio arrived in Riyadh, Saudi Arabia for planned meetings with Russian officials to discuss the future of the Russia-Ukraine war. European leaders and President Volodymyr Zelensky of Ukraine have expressed surprise and frustration at being sidelined from the talks.

Mr. Zelensky was in the United Arab Emirates on Monday for a track of negotiations with Russia that is separate from the Trump administration’s effort, focusing on prisoner exchanges and returning Ukrainian children from Russia. He reiterated that Ukraine would accept no terms negotiated between Russia and the Trump administration without Ukrainian participation, and confirmed that Ukrainian representatives would not be at the talks in Saudi Arabia.

Andrew E. Kramer contributed reporting from Kyiv, Ukraine.

With his unapologetic conservatism, his vow to fix a “broken” nation, his “common sense” fight against elites and all things woke, his norm-shattering personal attacks against political rivals, his pugilistic use of demeaning nicknames and his open disdain of the news media, Pierre Poilievre, the front-runner to become Canada’s next leader, has become a darling of the American right.

Some of President Trump’s most prominent supporters have publicly showered Mr. Poilievre, the leader of the main opposition Conservative Party, with compliments — a remarkable feat given that Canadian opposition leaders tend to attract little attention in the United States, much less praise.

But when Elon Musk, the world’s richest man who is leading an aggressive campaign against the U.S. federal bureaucracy on behalf of Mr. Trump, recently endorsed Mr. Poilievre as Canada’s next leader, Mr. Poilievre found himself in an uncomfortable situation.

Asked at a news conference last month whether he accepted the endorsement, Mr. Poilievre said, “My three-year-old has just told me that he wants to go to Mars, so I guess then Mr. Musk would be the right guy to put him in touch with,” before adding that it would be great if Mr. Musk opened some Tesla factories in Canada.

Mr. Poilievre’s backing by people close to Mr. Trump was always a double-edged sword in Canada, where the U.S. president is popular among hardcore conservatives but not among mainstream voters.

But that support now risks becoming a liability as Canada confronts a once unimaginable threat: the president of the United States, Canada’s closest ally, repeatedly questioning Canada’s viability as a nation, threatening to annex it through economic force and denigrating its prime minister as a “governor.”

As patriotic feelings have surged in Canada, Mr. Poilievre’s lead has narrowed significantly in several polls. Until a month ago, Mr. Poilievre, 45, appeared to be a shoo-in to become Canada’s next leader after having built a double-digit lead in the polls by channeling national frustration and anger at the deeply unpopular prime minister, Justin Trudeau.

Mr. Trudeau is expected to step down next month as prime minister after his Liberal Party selects a successor, who will automatically become prime minister. A general election is then likely to be held a couple of months later.

“For Poilievre, the biggest challenge is that for the last two years the villain in his story was Justin Trudeau,” said David Coletto, the founder of Abacus Data, a polling firm. “But that villain is now leaving, and there’s a new, bigger, badder villain that is coming from outside the country — and that’s Donald Trump.”

“What Canadians are now trying to figure out is who’s the hero in that story, who’s going to save them and protect them against that threat,” Mr. Coletto added. “And the conclusion that more people are going to choose Pierre Poilievre is now up in the air.”

Mr. Poilievre has responded by toning down his attack-dog persona and by switching to a “Canada First” message that he emphasized at a rally in Ottawa over the weekend. Before hundreds of supporters, Mr. Poilievre spent much of his speech responding to the threat from the United States, vowing to “bear any burden and pay any price to protect our sovereignty and independence.’’

A spokesman for Mr. Poilievre did not respond to requests for an interview.

Mr. Poilievre’s supporters said he was simply adjusting to external developments and that he remained true to his long-held core conservative principles.

Ginny Roth, a partner at Crestview Strategy and a former communications director for Mr. Poilievre, said that Canada First was “a turning away from a naïve, international liberalism that saw global elites put the interests of their own business and, frankly, coupled with left-wing causes, ahead of the interests of regular working people.”

Ms. Roth attributed Mr. Poilievre and the Conservatives’ dip in the polls to a blip enjoyed by the Liberals after Mr. Trudeau’s resignation announcement, as well as a temporary “rally-around-the-flag” reaction among voters to Mr. Trump’s imposition of tariffs and his annexation threats.

No matter how the polls evolve, Mr. Poilievre’s situation shows how Mr. Trump’s aggressive foreign policy has upended the domestic politics of a major ally, experts said.

“With the Trump administration in power again, wreaking havoc in so many ways, including trade with Canada, it puts Mr. Poilievre in a very difficult position,” said Jonathan Malloy, an expert on Canadian politics at Carleton University. “I think he’s going to have to differentiate himself from Mr. Trump, much more than he was planning to. His opponents, of course, will accuse him of being Trump-lite.”

A career politician, Mr. Poilievre has been known for his combativeness since being elected to Parliament in 2004 at the age of 25. But it is in the last few years that he has embraced the tactics and messages used by Mr. Trump and others, portraying himself as an outsider fighting against a corrupt political, business, academic and media establishment.

He won the leadership of the Conservatives in 2022, after championing more than any other politician the truckers who took over and paralyzed Ottawa, the capital, for weeks to protest anti-COVID mandates. In the past two years, he pummeled Mr. Trudeau and other politicians with a constant barrage of personal insults and attacks that is new to Canadian politics.

Mr. Poilievre has given rivals insulting nicknames, including “Trust Fund Trudeau” to Mr. Trudeau, the son of a former prime minister, and “Sellout Singh” to the leader of the New Democrats, a smaller left-leaning party. Like Mr. Trump, he often says that problems can be solved with “common sense” — a term used by populists to pit ordinary people against a supposedly misguided and corrupt elite, said Emily Laxer, an expert on populism at York University.

While Mr. Poilievre’s policies are based on traditional conservative ideas of small government, free market and lower taxes, his populist tactics are a break from the past in Canada, Ms. Laxer said.

“There is evidence of a kind of mimicking of Trump’s messaging and strategy,” Ms. Laxer said. “And certainly, they both have benefited from the polarization of their societies, politically, and they’ve contributed to that polarization.”

Mr. Poilievre’s campaign against what he perceives as woke and the news media, vowing to get rid of the public broadcaster, CBC, has further endeared him to Fox News, Joe Rogan, Mr. Musk and other high-profile supporters of Mr. Trump, who tend to dislike Mr. Trudeau.

Mr. Musk described as a “masterpiece” a video in which Mr. Poilievre, while eating an apple, spars with a reporter questioning him about his use of populism. Bill Ackman, the hedge fund billionaire, posted that Mr. Poilievre was “extremely impressive” and “should be Canada’s next leader,” adding, “Make Canada Great Again.” Mr. Musk responded with a 100 percent emoji.

Fred Delorey, a former national campaign manager for the Conservative Party, said that Mr. Poilievre had elicited that kind of reaction because of the power of his message.

“I’ve never seen a Canadian conservative leader resonate outside the country like Poilievre does,” said Mr. Delorey, now chair of Northstar Public Affairs. “His style is direct to the point, and I think people appreciate that.”

Mr. Delorey said that the American right’s favorable comments about Mr. Poilievre would not have an effect on Canadian voters. Mr. Poilievre, he said, should stay focused on his message, “on what matters. Who cares if someone likes him or doesn’t like him.”

But Mr. Coletto, the pollster, said that these endorsements and Mr. Poilievre’s attitude toward the American president will be factors in a general election that has abruptly shifted from being about Mr. Trudeau to being about Mr. Trump.

“There is a subset of Conservative supporters who actually like Donald Trump, even today, despite everything he’s done,” Mr. Coletto said. “But Poilievre’s got an equally large part of his base that doesn’t.”

And during the upcoming general election campaign, Mr. Poilievre’s rivals are likely to seize on the endorsements, Mr. Coletto said, adding, “It’s common in campaigns to remind voters of who likes who.”

The Israeli military said on Monday that it will keep forces in five locations in southern Lebanon after a deadline for its full withdrawal lapses on Tuesday. The announcement raised fears of a resurgence in violence in southern Lebanon between Israel and Hezbollah.

After more than a year of war, the two sides reached a cease-fire in late November that was contingent on both Israel and Hezbollah ceding control of southern Lebanon to the Lebanese military by the end of January. Hezbollah had long dominated the region, while Israel had captured large parts of it after invading Lebanon in September.

In late January, mediators announced a three-week extension to that agreement, giving Israel more time to complete its withdrawal. The truce has frequently been punctured by bursts of violence — including an Israeli airstrike on Monday that killed a Hamas leader in southern Lebanon — but neither side has reverted to full-scale war.

Now, the specter of renewed conflict looms once more after the Israeli military announced that it will keep some troops in Lebanon beyond the Feb. 18 deadline, potentially preventing some Lebanese civilians from returning home.

“We will leave small amounts of troops deployed temporarily in five strategic points along the border in Lebanon so we can continue to defend our residents and to make sure there’s no immediate threat,” said Lt. Col. Nadav Shoshani, a military spokesman, in a briefing for reporters on Monday afternoon.

Colonel Shoshani named several locations spread along most of the length of the 75-mile border, including places across the border from Israeli villages that were badly damaged by Hezbollah rocket fire during the war. He said that Hezbollah had not lived up to its own side of the November agreement and still posed a threat to Israeli residents in those areas. He declined to say how long the occupation would last. It is unclear to what extent Hezbollah has a presence in those areas.

Hezbollah’s leader, Naim Qassem, vehemently opposed the idea of Israel keeping troops inside Lebanon during a speech on Sunday. But he stopped short of pledging to resume attacks against Israel.

“Israel must withdraw completely on Feb. 18,” Mr. Qassem said. “This is the agreement.”

“Everyone knows how an occupation is dealt with,” he warned, without giving further details.

The war between Hezbollah and Israel broke out after the Lebanese militia started firing on Israeli military positions in solidarity with its ally Hamas, shortly after Hamas attacked Israel in October 2023.

The conflict remained largely contained to back-and-forth missile and rocket strikes, displacing thousands on either side of the border, until it erupted into a full frontal war and wide-scale Israeli bombardment of Lebanese cities in the second half of 2024.

Israel killed much of Hezbollah’s leadership in an aerial campaign and invaded large swaths of southern Lebanon, in moves that collectively displaced more than a million people in Lebanon.

Israel said its intention was to prevent Hezbollah from posing a threat to residents of northern Israel, some 60,000 of whom were forced to leave their homes because of Hezbollah rocket fire.

Gabby Sobelman contributed reporting.

Nearly 40 years after she was born with a malformed spine and misshapen limbs — most likely because her father was exposed to Agent Orange, the toxic chemical that the American military used during the Vietnam War — Nguyen Thi Ngoc Diem finally got some help from the United States.

A project funded by U.S.A.I.D. gave her graphic design training in 2022 and helped her land a job. Even when the company closed a few months ago, she stayed hopeful: The same program for Agent Orange victims was due to deliver a new computer, or a small loan.

I was the first to tell her that the support may never come; that President Trump had frozen U.S.A.I.D. funding and planned to fire nearly everyone associated with the humanitarian agency.

“It makes no sense,” Ms. Diem told me, her tiny body curled into a wheelchair, below a crucifix on the wall. “Agent Orange came from the U.S. — it was used here, and that makes us victims,” she said. “A little support for people like us means a lot, but at the same time, it’s the U.S.’s responsibility.”

As Mr. Trump and Elon Musk gut U.S.A.I.D., this can now be added to the list of effects: Two months before the 50th anniversary of the Vietnam War’s end, with ceremonies already planned, they have demolished the main American outlet for making amends, shaking the foundation of a partnership meant to be a bulwark against China.

As many as three million Vietnamese have been affected by Agent Orange, including more than 150,000 children born with serious developmental problems.

Addressing the painful legacy of the chemical’s wartime use as a defoliant, along other issues tied to American military involvement in Vietnam, has offered the U.S. a chance to fuse past and present, soft power and hard power, in the service of courting a rising regional power.

That’s now halted. Bulldozers that were cleaning up contamination at a former American air base in southern Vietnam — which both countries might eventually want to use — have gone silent. Around 1,000 mine-removal workers in central Vietnam have been sent home.

And with the suspension of aid for Agent Orange victims, along with efforts to find and identify Vietnam’s missing war dead, Mr. Trump has essentially stalled 30 years of progress in bringing together former enemies, including two militaries still feeling out whether to trust one another.

While Vietnam’s leaders have tread carefully with the Trump administration, hoping to avoid its punitive tariffs, they have lamented the loss of war legacy programs. They have long viewed the work as a prerequisite for almost everything else.

American officials who spent a lifetime building bilateral bonds are especially furious, signing open letters of complaint and condemning what they see as a plainly misguided move.

“One thing I know about the Vietnamese is that they want to know they can depend on us; that we won’t lose interest and walk away,” said Tim Rieser, a former foreign policy aide to Senator Patrick J. Leahy, a Vermont Democrat who led legislative efforts on war legacy issues before retiring in 2023. “And that’s what the Trump administration is doing.”

American military commanders see Vietnam, with its strategic location, as vital for maintaining stability in Asia, especially as China has become more aggressive around the shipping lanes and islands off the Vietnamese coast.

U.S. Navy warships have made several port visits to Vietnam since 2018. More are expected. And in a sign of Pentagon support for aid as a tool of alliance-building, half of the funding that U.S.A.I.D. manages for Agent Orange cleanup comes from the Defense Department.

Perhaps some of that will survive. According to the official account of a call on Feb. 7 between Defense Secretary Pete Hegseth and Vietnam’s defense minister, Gen. Phan Van Giang, Mr. Hegseth “underscored the department’s support for ongoing efforts to collaborate on legacy of war issues.”

A federal judge on Thursday ordered the Trump administration to temporarily lift the U.S.A.I.D. funding freeze, setting a Tuesday deadline for evidence of compliance.

But as of Monday in Vietnam, the work stoppage was still in effect. Even if funding returns, in a year meant to mark recovery from the darkness of a cruel war, fundamental damage has already been done in ways that feel — for partners and victims in both countries — like a knife shoved into old wounds.

From Enemies to Partners

Combat veterans were the original reconcilers. At first, they partnered up at the squad level, to rid battlegrounds of unexploded ordnance. But once Washington and Hanoi got on board, bigger problems were tackled, starting with Da Nang Airport, a former American military base near the old dividing line between North and South Vietnam.

It had been a centerpiece of the campaign to clear vegetation with Agent Orange, named for the colored stripe on its barrels and notorious for containing 2,3,7,8-tetrachlorodibenzo-p-dioxin — one of the most noxious substances ever created.

At the start, no one knew if the airport’s poisoned land could be made safe. The projected cost of remediation tripled. But after seven years and more than $115 million in U.S. assistance, it was clean. So clean that Mr. Trump landed there with Air Force One in 2018.

Bien Hoa air base, about 20 miles outside Ho Chi Minh City, formerly Saigon, is a tougher challenge: a 10-year, $450 million project involving the treatment of enough contaminated earth to fill 200 Olympic-sized swimming pools. The United States has contributed more than $160 million so far, out of a pledge of $300 million under U.S.A.I.D. management.

Tetra Tech, an American engineering firm hired by U.S.A.I.D. for part of the project, did not respond to emails asking about its status.

When I visited the busy neighborhood around the base last week, a Vietnamese military officer confirmed that the cleanup had been halted, creating anxiety in the city. Many of the homes nearby had been inside the base’s perimeter, until its footprint was condensed.

Dinh Thi Lan, 56, told me that in 1991, she was one of the first to move onto a street that abutted the base and a contaminated lake. During seasonal floods, she said, fish would sometimes flop out.

“I ate the fish,” she said. “I’m worried.”

Behind her, in a back room, I could see a photo of a bright-eyed man with thick hair, above candles on a dark wood table.

“My husband,” she told me. “He died of stomach cancer in 2009. He was 39.”

Searching for Impact

During the war, Dong Nai Province, with Bien Hoa at its southeastern edge, became a logistics hub for North Vietnamese soldiers as they prepared to take Saigon.

Before that, the U.S. military had tried to strip the verdant landscape of food and cover.

Pilots usually flew 150 feet from the ground. They sprayed 56 percent of Dong Nai with nearly 1.8 million gallons of Agent Orange — more than in any other province in Vietnam.

Truong Thi Nguyet, 75, joined the guerrilla ranks in Dong Nai at 16. After the war, she founded one of Vietnam’s first rehabilitation centers for people with disabilities caused by Agent Orange, which the United States banned in 1971.

In remote villages, she found dozens of boys and girls with missing or malformed limbs, deafness, cerebral palsy, cognitive impairment and sometimes all of the above. One morning, she discovered a poor family so overwhelmed that they had put their severely disabled daughter in a cage outside.

“I never thought I would tell anyone this story,” Ms. Nguyet said when I visited her home in Dinh Quan township. “It was so painful, and I was so angry.”

“I tried to raise some money and convince the family to build a small room in the house,” she added. “After a while, with some financial support, they did.”

Most of the funding for the rehab center comes from the Vietnamese government. But a sign over the door declares that U.S.A.I.D. provided equipment in 2020: a few desks and a metal bed; a playroom with a climbing wall and a pool of candy-colored plastic balls.

Since 1991, according to the State Department, the U.S. government has contributed about $155 million to improve the lives of people with disabilities in areas affected by Agent Orange and leftover explosives.

The U.S.A.I.D. program that benefited Ms. Diem, the graphic designer, is limited in scope. Last year, just 45 Agent Orange victims in Dong Nai (out of 9,000) received no-interest loans of a little under $800. Some bought scooters, and others invested in goats, said Nguyen Van Thinh, 47, the leader of a club that has 260 members with disabilities.

Ms. Diem was among 11 women who were approved for smaller loans this year under a “social inclusion” program. Her commitment and grit are undeniable. After high school, she went to college away from home, persuading friends and strangers to carry her to class or the bathroom. She earned a degree in information technology.

Now, all she wants is a computer for doing her design work — support she was promised by the United States, which contaminated her country and gnarled her body.

“I want to feel connected with the world,” she told me. “I want to be less of a burden.”

Pope Francis will remain in a Rome hospital after being admitted late last week following a series of tests that indicated a “complex clinical picture,” the Vatican said on Monday, raising fresh concerns about the 88-year-old pontiff’s health.

Diagnostic tests carried out after Francis was taken to Policlinico A. Gemelli on Friday presented “a polymicrobial respiratory tract infection,” and his doctors had changed treatment accordingly, the Vatican said in a statement.

The complex clinical picture “would require an appropriate medical stay,” it said, without elaborating.

Subscribe to The Times to read as many articles as you like.

President Trump says he wants to “make a deal” to “STOP this ridiculous war” in Ukraine. His call with President Vladimir V. Putin, and a meeting expected this week between U.S. and Russian officials in Saudi Arabia, have raised expectations that negotiations could end three years of fighting.

But how would those talks actually work? Who would be involved? What could a deal look like?

The New York Times has been reporting on these questions since the early weeks of the war in 2022, when Ukraine and Russia held direct talks that failed to reach a peace agreement.

To sum up what we know at this point, here’s our guide to potential Ukraine peace talks.

Right now, Ukraine has few options for reversing Russia’s recent gains on the battlefield. That means that any deal is likely to involve painful concessions by Ukraine, which could be seen as Mr. Trump’s rewarding Mr. Putin’s aggression. It also means that Russia will almost certainly drive a hard bargain.

But Mr. Putin may have his own incentives for making a deal. Russia’s economy risks runaway inflation amid enormous spending on the war, while the military is suffering some 1,000 or more casualties a day. And a settlement over Ukraine could pave the way for a reduction of Western sanctions.

The talks would be exceedingly complicated. Many doubt that Mr. Putin will negotiate in good faith, while Europe and Ukraine fear that Mr. Trump will be tempted to strike a deal with the Kremlin over their heads.

Still, Russia and Ukraine did make headway toward striking a deal when they last negotiated directly, back in the spring of 2022. And some experts believe that an agreement is possible that would satisfy Mr. Putin while preserving some form of sovereignty and security for Ukraine.

Who’s at the table?

The Biden administration sought to isolate Russia diplomatically and said any negotiations about Ukraine’s fate had to involve the Ukrainians. Mr. Trump broke from that approach on Feb. 12, when he discussed Ukraine in a lengthy call with Mr. Putin and then said he would “inform” Ukraine’s president, Volodymyr Zelensky, of the conversation.

Now it’s Ukraine that appears isolated. Mr. Zelensky said he was not invited to discussions this week between top aides to Mr. Trump and their Russian counterparts in Saudi Arabia.

European countries may also be cut out — even though Europe’s total aid to Ukraine since the start of the war, roughly $140 billion, is greater than what the United States has provided.

Mr. Trump said he would “probably” meet Mr. Putin in Saudi Arabia soon. Qatar, the United Arab Emirates and Turkey have already been mediating between Ukraine and Russia on matters like prisoner exchanges and navigation in the Black Sea.

Territory

Ukraine has said it will never recognize any change to its borders. Russia claims not just the roughly 20 percent of the country it already controls, but also a swath of Ukrainian-held land in four regions that it does not fully control.

A possible compromise: freeze the fighting.

Russia keeps control of the land it has already captured but stops fighting for more. Ukraine and the West don’t formally recognize Russia’s annexation, even as Russia retains its broader territorial claims. An agreement could stipulate that territorial disputes will be resolved peacefully at some point in the future — say, 10 or 15 years, as Ukrainian negotiators proposed for the status of Crimea in the 2022 peace talks.

And a wrinkle: Kursk.

Ukraine still holds around 200 square miles of territory in Russia’s Kursk region. Russia has rejected the idea that Ukraine could use that land as a bargaining chip in any future talks. But if talks start before Russia has managed to expel Ukrainian troops from there, Ukraine may still be able to find a way to trade a retreat from Kursk for concessions by Russia.

NATO and the E.U.

While Ukraine wants to reclaim the territory Russia has captured, it has also made clear that its future security is at least as important, meaning protection from renewed Russian aggression.

Ukraine describes NATO membership as the key to this protection. Russia describes the possibility of Ukraine joining the alliance as an existential threat to its own security.

The Trump administration has already made it clear that it expects Russia to get its way here.

Leaving open a path for Ukraine to join the European Union, but not NATO, could be presented as a compromise. Before the 2022 peace talks failed, Russian negotiators agreed to language in the draft treaty that said the deal would be “compatible with Ukraine’s possible membership in the European Union.”

Security guarantees

Absent NATO membership, Mr. Zelensky has floated the deployment of 200,000 foreign troops to Ukraine to safeguard any cease-fire. Analysts say the West can’t produce such a large force. Keir Starmer, the British prime minister, said on Sunday that his country would be ready to commit an unspecified number of peacekeeping troops.

But Russia wants its own “security guarantees” to assure that Ukraine won’t try to rebuild its military capacity and recapture Russian-occupied land. It wants to cap the size of Ukraine’s military and ban foreign troops from the country.

Threading this needle is widely seen as the trickiest aspect of any negotiation. A team of experts led by Marc Weller, a Cambridge international law professor who specializes in peace negotiations, has drafted a potential agreement that envisions a compromise: deploying a small international force of 7,500 staffed by countries acceptable to both Russia and Ukraine to keep the peace at the front line.

The Weller proposal envisions immediate sanctions against either side if it restarts hostilities. It would allow Ukraine to hold limited joint exercises with other countries and cooperate with them on weapons production and military training.

There would be no permanent deployment of foreign troops, but Ukraine could host a small number of technical personnel. And Ukraine would agree to a ban on missiles with a range of more than 155 miles.

Cease-fire mechanics

The durability of any peace could hinge on the nuts and bolts of a cease-fire agreement.

Thomas Greminger, a former Swiss diplomat who was involved in monitoring the cease-fire in eastern Ukraine after 2015, flags three key issues.

The first is agreeing on the “line of contact” separating Russian from Ukrainian-controlled territory. Next there would need to be a “disengagement zone,” or buffer, between opposing forces, to prevent stray gunfire or misunderstandings from flaring into combat. Third, he said, there will need to be some way to hold both sides to account for cease-fire violations.

The language in the agreements “could be very technical” on issues like the disengagement zone and cease-fire enforcement, said Mr. Greminger, now the director of the Geneva Center for Security Policy think tank. But, he said, that language could be “quite decisive over whether the cease-fire holds.”

NATO in Eastern Europe

Mr. Putin claims his war isn’t just about Ukraine, but about forcing the West to accept a new security architecture in Europe.

Weeks before the invasion, he presented an ultimatum demanding that NATO stop expanding eastward and withdraw from much of Europe. And in his Feb. 12 call with Mr. Trump, Mr. Putin warned of “the need to eliminate the root causes of the conflict,” the Kremlin said.

That means Russia is likely to make demands that go well beyond the fate of Ukraine itself.

America’s allies are likely to argue that a retreat of NATO in Europe will increase the risk of a Russian invasion for countries like Poland and the Baltics. But Mr. Trump might be amenable to such a deal, given his skepticism about American deployments abroad.

All this will make for an incredibly complicated negotiation. Mr. Greminger, who has been working with experts close to governments with a stake in the war to game out how the talks could go, sees at least three negotiating tracks: U.S.-Russian, Russian-Ukrainian and Russian-European.

“You have at least these three levels,” he says. “There are no shortcuts.”

Trump and Putin

Mr. Putin also has demands that go beyond territory and security. In the 2022 peace talks, Russian negotiators sought to strip away Ukrainian identity, demanding that the country make Russian an official language and ban naming places after Ukrainian independence fighters. Those issues are likely to come up again.

Mr. Putin could also try to leverage a Ukraine settlement to get other benefits from Mr. Trump, like sanctions relief. But it is his apparent desire for a grand bargain with Washington, some analysts believe, that could represent his greatest incentive to cut a deal.

“Putin would like to have a longer-term, productive relationship with this administration,” said Rose Gottemoeller, a former American under secretary of state with experience negotiating with the Russians. “He needs to be willing to make concessions.”

Andrew E. Kramer contributed reporting.