Trump has repeatedly criticised NATO countries, at one point saying he would encourage Russia to do “whatever the hell it wants” to allies that did not pay their way.
The incoming president has also previously expressed admiration for Russian President Vladimir Putin – but Biden mocked Putin over the progress of Moscow’s invasion of Ukraine.
“When Putin invaded, he thought he’d conquer Kyiv in a matter of days. The truth is, since that war began I’m the only one that stood in the centre of Kyiv, not him,” said Biden.
Biden became the first sitting US president to visit a warzone not controlled by American forces when he made a top-secret visit to Ukraine’s capital in 2023.
He said the United States and its allies “can’t walk away” from Ukraine, to which Washington has sent billions of dollars in military aid since the war started in 2022.
