Zelenskyy was among the first leaders to congratulate Trump, who has criticised the scale of US support for Ukraine.

United States President Joe Biden plans to rush billions of dollars in security assistance to Ukraine before he leaves office in January, reports say, hoping to shore up the government in Kyiv before Donald Trump returns to the White House.

Trump, who won Tuesday’s election, has criticised the scale of US military and financial support for Ukraine and has pledged to end the war with Russia quickly – without saying how.

His position on Ukraine has raised concerns about the future of Washington’s support for Ukraine’s war with Russia under a Republican-controlled White House, Senate and possibly the House of Representatives.

“The administration plans to push forward … to put Ukraine in the strongest position possible,” a senior Biden administration official told the Reuters news agency on condition of anonymity in a report published on Thursday. Biden’s plans for the transfers were first reported by Politico.

Ukrainian President Volodymyr Zelenskyy was among the first world leaders to congratulate Trump and he also spoke to the president-elect on Wednesday.

“We agreed to maintain close dialogue and advance our cooperation. Strong and unwavering U.S. leadership is vital for the world and for a just peace,” Zelenskyy said in a post on social media platform X.

The US House approved aid for Ukraine in April, including an allocation for weapons.

Of the weapons transfer authority passed, $4.3bn remains, in addition to $2.8bn worth of transfers lawmakers approved in previous spending measures and $2bn in funding for new weapons purchases.

In total, that $9bn in military assistance would be a significant boost to Ukraine’s defence.

There was no immediate response from the White House.

Since Russia’s full-scale invasion of Ukraine in 2022, the US has already provided more than $64.1bn in military assistance to Ukraine, according to the latest data by the US Department of State.

To help Ukraine retake its territory in its ground war with Russia, more ground vehicles will be needed, as well as 155mm artillery and surface-to-surface missiles.

Some analysts say it is by no means certain Washington would back any more Ukraine assistance once Republicans control the White House and at least half of Congress, especially as Ukraine experiences battlefield setbacks.

Senate Republican leader Mitch McConnell declined to discuss aid for Ukraine at a news conference on Wednesday, saying he was there only to discuss election results.

During the campaign, Trump had insisted that Russian President Vladimir Putin would never have invaded Ukraine in 2022 had he been in office, adding that he “could solve that in 24 hours”.

Trump had suggested that Ukraine might have to cede territory to Russia to reach a peace deal, something Ukraine has rejected and Biden has never suggested.

Vice president-elect JD Vance has also been a vocal critic of Ukraine assistance, arguing that government funds would be better spent on domestic priorities.