The US has given $20bn (£15bn) to Ukraine, funded by the profits of seized Russian assets.
The economic support forms a significant part of a $50bn (£39bn) package agreed by G7 member nations announced in June.
Funding the aid through frozen assets means Russia has to "bear the costs of its illegal war, instead of taxpayers," US Treasury Secretary Janet Yellen said.
It comes a matter of weeks before US President Joe Biden is replaced by Donald Trump, who has said he wants to end the war in Ukraine quickly upon taking office.
