Israel on Sunday deployed forces to a "demilitarised buffer zone" in southwest Syria abutting the Israeli-occupied Golan Heights after Damascus fell to opposition forces.
Israel had already said the day before, as the rebels had swiftly advanced across Syria, that its soldiers had entered the UN-patrolled buffer zone to assist peacekeepers in repelling an attack.
On Sunday, the Israeli forces announced a troop deployment there, citing "the possible entry of armed individuals into the buffer zone".
"Following the recent events in Syria... the IDF (army) has deployed forces in the buffer zone and in several other places necessary for its defence, to ensure the safety of the communities of the Golan Heights and the citizens of Israel," a military statement said.
Israeli forces "will continue to operate as long as necessary in order to preserve the buffer zone and defend Israel", it added.
The statement added that the Israeli military was "not interfering with the internal events in Syria".
Since the rebel coalition, led by Hayat Tahrir al-Sham, began its renewed offensive against the forces of President Bashar al-Assad on 27 November, Syrian government forces have left positions near the Israeli-held Golan, according to the Syrian Observatory for Human Rights (SOHR).
Rami Abdel Rahman, head of the SOHR, said on Saturday that army forces had withdrawn from positions in Quneitra province, which includes part of the Golan Heights.
Most of the plateau has been occupied since 1967 by Israel, which later annexed it in a move not recognised by most of the international community.
In 1974 the buffer zone was established, separating the Israeli-held and Syrian territories, with UN peacekeepers stationed there since.
A UN Peacekeeping spokesperson said on Saturday that UNDOF personnel had observed "unidentified armed individuals in the area of separation, including approximately 20 who went into one of the mission's positions in the northern part of the area of separation".
The Israeli army said it was "assisting the UN forces in repelling the attack".
The UN spokesperson said that "peacekeepers continue to carry out their mandated activities on the Golan".
On Sunday, Lebanese media outlets reported an Israeli strike on Quneitra targeting an arms depot.
In a separate statement, the Israeli military said schools in the northern Golan Heights, in an area covering four Druze towns, would move to online teaching, also declaring a "closed military zone" in agricultural lands in the area.
Meanwhile, Israeli opposition leader Yair Lapid said the fall of Assad was an opportunity to "establish strong regional alliance with Saudi Arabia and the countries of the Abraham Accords to jointly confront regional instability".
"The Iranian axis of resistance has significantly weakened, and Israel must pursue a comprehensive diplomatic achievement that would also benefit us in Gaza and the West Bank."
Education Minister Yoav Kisch said to push for the postponement of Prime Minister Benjamin Netanyahu's court testimony scheduled for Tuesday, citing "regional instability".
Posting on his X account, Kisch wrote: "In light of the strategic changes in our region, the uncertainty, and the numerous challenges facing the Prime Minister and the State of Israel, I call on the judges and the prosecution to reconsider postponing the Prime Minister’s court appearance by three months."
"Given these dramatic developments, insisting on holding the hearing at this time would be a mistake and lack objectivity," Kisch added.
Agencies contributed to this report.