Israel struck multiple Syrian weapons depots and air defenses overnight and into Sunday, according to the Syrian Observatory for Human Rights, in what appeared to be the latest in a series of airstrikes that Israel has said are aimed at keeping military hardware and infrastructure out of the hands of extremists after rebels seized power a week ago.

In all, Israel struck its neighbor 75 times in attacks that began Saturday night near the Syrian capital, Damascus, and the cities of Hama and Homs, said the Observatory, a Britain-based monitoring organization that has long tracked the conflict in Syria.

Israel has struck Syria more than 450 times since the collapse of the al-Assad regime a week ago, according to the Observatory, destroying Syria’s navy and dozens of ammunition depots, air bases and other military equipment.

Israel’s military has also seized and occupied an expanse of territory in Syria over the de facto border between the two countries, giving no timeline for its departure apart from saying that it would stay until its security demands are met.

There was no immediate comment from the Israeli military about its latest strikes in Syria.

Neither the previous Syrian government of President Bashar al-Assad nor the new authorities in Damascus have attacked Israel, and Arab countries and France have called on Israel to withdraw and respect Syria’s sovereignty.

Israeli officials, however, say that the raids are necessary to secure the border and to keep Syria’s weaponry from falling into the hands of extremists while the country remains unstable.

With the Assad regime ousted, some fear a security vacuum that could allow the Islamic State or other extremist groups to rise up.

The group leading the rebel coalition that now governs Syria, Hayat Tahrir al-Sham, has long been designated as a terrorist organization by the United States and other Western countries, but has installed a technocratic administration in Damascus and promised moderate, tolerant governance. That has led some countries to consider lifting the terrorist designation to establish relations with Syria’s new leaders.

Visiting Israeli troops in the Golan Heights on Friday, Lt. Gen. Herzi Halevi, Israel’s military chief of staff, insisted his country was acting to secure its frontier and its citizens even as it crossed the lines established by a cease-fire agreement reached between Syria and Israel in 1974. Israel had no intention of interfering in the future of a post-Assad Syria, he said.

“There was a country here that was an enemy state, its army collapsed, and there is a threat that terrorist elements could reach here,” Lieutenant General Halevi said in remarks released by the military on Saturday.

“We moved forward so that these terrorist elements will not establish themselves — extremist terrorists will not establish themselves right next to the border,” he said. “We are not intervening in what is happening in Syria. We have no intention of managing Syria. We are unequivocally intervening in what determines the security of Israeli citizens here.”

The overnight airstrikes lasted for about eight hours, according to the Syrian Observatory for Human Rights, which said that weapons and ammunitions depots as well as bases in the mountains and countryside outside Damascus had been struck.

It said Israel had also targeted warehouses in the countryside outside the city of Homs, air defenses at the airport in the city of Hama and other sites.

Isabel Kershner contributed reporting from Jerusalem, and Rania Khaled from Cairo.