U.S. National Security Advisor Jake Sullivan will travel to Israel this week for talks on Syria following the fall of Bashar al-Assad, and on a truce deal in Gaza, the White House said Monday.

Sullivan will meet Israeli officials to discuss "efforts to reach a hostage release and ceasefire deal in Gaza, the latest developments in Syria, and for discussions about Lebanon and Iran," National Security Council spokesman Sean Savett said.

Large numbers of Syrians fleeing their country on Monday flocked to the Masnaa border crossing with Lebanon and some of them tried to force their way into the country without going through Lebanese General Security measures, General Security said.

Representatives of the United States, France, UNIFIL and the Lebanese and Israeli armies met Monday in Naqoura to “coordinate their support for the cessation of hostilities that went into effect on November 27,” the U.S. and French embassies and UNIFIL said in a joint statement.

“As set out in the (ceasefire) announcement, UNIFIL hosted the meeting, with the United States serving as chair, assisted by France, and joined by the LAF and IDF (Lebanese and Israeli armies),” the statement said.

Across Lebanon, the Middle East, and beyond, the fall of Syria’s authoritarian government at the hands of Islamist-led rebels set off waves of jubilation, trepidation and alarm.

Many Lebanese exulted at the overthrow of the Syrian leader while others worried about more instability rocking a region in turmoil.

MP Hassan Fadlallah announced Monday that “what’s happening in Syria is a major, dangerous and new transformation,” in the first comments by a Hezbollah official on the fall of Bashar al-Assad’s regime at the hands of Islamist-led rebels.

U.S. President Joe Biden has reassured that the United States “will support Syria's neighbors, including Jordan, Lebanon, Iraq and Israel should any threat arise from Syria during this period of transition.”

Lebanese Forces leader Samir Geagea has congratulated all Lebanese on the fall of Bashar al-Assad’s regime, saying that “over the past 50 years, the regime of Hafez and Bashar al-Assad was the biggest obstacle to the building of a state in Lebanon.”

The Israeli army released Monday two brothers it had detained Sunday near the Shebaa Farms.

The brothers Samer and Sameer Sinan from the town of Ain Qinya were detained as they harvested olives in al-Majidiya near the Shebaa Farms.

The Israeli military said Monday that four soldiers were killed in southern Lebanon, the first deaths announced in the area since the start of a ceasefire with Hezbollah 12 days ago.

The four reservists, all from the same battalion, "fell in combat" on Sunday, the military said without giving further details.

The Lebanese Army said one person was killed and four soldiers wounded Monday in an Israeli strike in the country's south, where a fragile ceasefire between Hezbollah and Israel came into force last month.

"The Israeli enemy targeted a car near the Saf al-Hawa/Bint Jbeil military checkpoint, killing a citizen and lightly wounding four soldiers," the army said in a statement.