WASHINGTON -- US President Joe Biden in remarks Sunday from the White House laid out a three-pronged policy forward as the opposition forces in Syria seized control of the capital, warning against any extremists' threats.

Bashar al-Assad has left Syria and resigned as the country's president while calling for a peaceful transfer of power, the Russian Foreign Ministry said in a statement on Sunday.

Speaking from the Roosevelt Room of the White House, Biden said his administration will help fend off potential threats against US partners in the region, including Jordan, Lebanon, Iraq and Israel, "during this period of transition."

Second, the president said, the United States will help ensure stability "in eastern Syria, protecting any personnel, our personnel, against any threats," and maintain the US mission against the extremist group known as Islamic State of Iraq and Syria (ISIS).

"We're clear-eyed about the fact that ISIS will try to take advantage of any vacuum to re-establish its capabilities and to create a safe haven. We will not let that happen," Biden said.

Third, the United States "will engage with all Syrian groups, including within the process, led by the United Nations, to establish a transition away from" the Assad government.

With less than two months in office, it's unclear, though, to what extent the Biden administration will fulfill the policy announced above.

Donald Trump, the incoming president who will assume office on Jan. 20, also reacted to the rapidly unfolding situation in Syria, calling for a hands-off approach from the United States.

"In any event, Syria is a mess, but is not our friend, & THE UNITED STATES SHOULD HAVE NOTHING TO DO WITH IT. THIS IS NOT OUR FIGHT. LET IT PLAY OUT. DO NOT GET INVOLVED!" Trump wrote on Truth Social on Saturday morning.

Also on Saturday, Jake Sullivan, Biden's national security advisor, told a defense forum in California that the United States won't get involved militarily in the current fight in Syria.