The president-elect advised Putin not to escalate the Ukraine war, a source said, as President Biden plans to urge Trump not to abandon Kyiv.

Cease-fire talks mediated by the United States, Qatar and Egypt have repeatedly stalled, as have parallel efforts by the U.S. and others to halt the fighting between Israel and Hezbollah in Lebanon.

President Biden extended the invitation to his former rival as part of a longstanding tradition to help ease the transition to a new administration.