The Syrian government collapsed after a surprise rebel offensive.
Rebel forces in Syria captured the capital Damascus and toppled the regime of President Bashar al-Assad in a lightning-quick advance across the country.
As Assad resigned and fled Syria, rebel forces moved into Damascus as citizens celebrated there and in the streets of Aleppo, where the rebel offensive began 11 days ago.
Meanwhile, the ceasefire in Lebanon is holding despite ongoing Israeli airstrikes on Hezbollah targets, which Israeli officials say are responses to ceasefire violations by the Iranian-backed militant group.
The Israel Defense Forces continued its intense airstrike and ground campaigns in Gaza, particularly in the north of the devastated Palestinian territory.
Tensions also remain high between Israel and Iran after tit-for-tat long-range strikes in recent months and threats of further military action from both sides.
Bashar al-Assad and his family are now in Moscow, Russian state-owned news agency TASS is reporting, citing a source in the Kremlin.
-ABC News' Tanya Stukalova
President Biden is expected to deliver remarks on Syria at 1 p.m. ET in the Roosevelt Room at the White House.
-ABC News' MaryAlice Parks, Cheyenne Haslett and Lauren Peller
The Iranian Foreign Ministry released a statement Sunday saying it continues to monitor the situation in Syria and that "the future of Syria will only be decided by the people."
"It is expected that the relations between Iranian and Syrian nations continue with a long-term and wise approach, based on common interests and benefits," the statement read, in part.
-ABC News' Somayeh Malekian
President Joe Biden will meet with his national security team on Sunday to get an update on the situation in Syria, the White House said.
-ABC News' Lauren Peller
