US National Security Adviser Jake Sullivan has clarified President Joe Biden's comments on Sunday that Ukraine does not need F-16 fighter jets yet.

Sullivan reiterated that the White House is prioritising the immediate needs of this war and will continue to do so.

"Every phase of this war, the president has tried to make sure that the Ukrainian military gets what they need," Sullivan said in an interview on the TV channel ABC.

"In the first phases, they were defending Kyiv. That was Javelin anti-tank weapons and Stinger anti-air systems. And that worked. It helped Ukraine defend Kyiv. In the second phase, it was heavy artillery to help them hold against the Russians pushing in eastern Ukraine. In this phase, the critical element is ground manoeuvre capability. And that means tanks, armoured personnel carriers, infantry fighting vehicles."

According to Sullivan, "what the president is saying is, he’s focused on those capabilities".

"The F-16 question is a question for later," Sullivan said in another interview on CNN, adding: "Therefore, President Biden said that he's not making any progress with it right now".

President Volodymyr Zelenskyy said that three other European countries, in addition to Poland, expressed their readiness to start training Ukrainian pilots on F-16 fighters.