US president-elect Donald Trump has spoken to Russian President Vladimir Putin, advising him not to escalate the Ukraine war, a source familiar with the conversation told Reuters.

It came amid reports outgoing President Joe Biden plans to urge Trump not to abandon Kyiv.

The White House confirmed on Sunday that Trump had accepted Biden’s invitation to a lunch meeting on Wednesday (US time).

Incoming first lady Melania Trump has also been invited to the White House to meet first lady Jill Biden. It is unclear when that might happen.

Confirmation of the conversation with Putin came after Trump spoke to Ukrainian President Volodymyr Zelensky last Wednesday, just one day after the US election.

Trump advised Putin not to escalate the war in Ukraine and reminded him of “Washington’s sizeable military presence in Europe”, The Washington Post reported.

Trump has criticised the scale of US military and financial support for Kyiv, vowing to end the war quickly without saying how.

Ukraine’s foreign ministry said it was not informed in advance of the call between Trump and Putin and could neither endorse or object to it.

“We do not comment on private calls between president Trump and other world leaders,” Trump communications director Steven Cheung said when asked about the phone call, which was first reported by The Post.

The Russian embassy in Washington did not immediately respond to a request for comment.

Republican Trump will take office on January 20 after defeating Vice President Kamala Harris in last week’s US election.

US National Security Adviser Jake Sullivan said Biden’s top message will be his commitment to ensure a peaceful transfer of power, and he will also talk to Trump about what’s happening in Europe, in Asia and the Middle East.

“President Biden will have the opportunity over the next 70 days to make the case to the Congress and to the incoming administration that the United States should not walk away from Ukraine, that walking away from Ukraine means more instability in Europe,” Sullivan told CBS News’ Face the Nation show.

Sullivan’s comments came as Ukraine attacked Moscow on Sunday with at least 34 drones, the biggest drone strike on the Russian capital since the beginning of the war.

Asked if Biden would ask Congress to pass legislation to authorise more funding for Ukraine, Sullivan deferred.

“I’m not here to put forward a specific legislative proposal. President Biden will make the case that we do need ongoing resources for Ukraine beyond the end of his term,” Sullivan said.

Trump has reportedly called Putin, according to Washington Post.

“Trump’s calls with world leaders are not being conducted with the support of the State Department and U.S. government interpreters.”

Main points:
– Advised Putin not to escalate war with Ukraine
– Reminded Putin… pic.twitter.com/uYef0fZMwe

— KyivPost (@KyivPost) November 10, 2024

Washington has provided tens of billions of dollars worth of US military and economic aid to Ukraine since it was invaded by Russia in February 2022, funding that Trump has repeatedly criticised and rallied against with other Republican lawmakers.

Trump insisted last year that Putin never would have invaded Ukraine if he had been in the White House. He told Reuters Ukraine may have to cede territory to reach a peace agreement, something the Ukrainians reject and Biden has never suggested.

Zelensky said on Thursday he was not aware of any details of Trump’s plan to end the Ukraine war quickly and that he was convinced a rapid end would entail major concessions for Kyiv.

According to the Government Accountability Office, Congress appropriated over $US174 billion ($264 billion) to Ukraine under Biden.

The pace of the aid is almost sure to drop under Trump with Republicans to take control of the US Senate with a 52-seat majority.

The 2½-year-old war in Ukraine is entering what some officials say could be its final act after Moscow’s forces advanced at the fastest pace since the early days of the war.

Moscow’s forces occupy about a fifth of Ukraine.

Russia says the war cannot end until its claimed annexations are recognised.

Kyiv demands all of its territory back, a position that has largely been supported by Western allies.

-with AAP