President Donald Trump said Tuesday that NATO countries should shoot down Russian aircraft that enter their airspace.

“Yes, I do,” Trump said when asked about Russia breaching the airspace of NATO allies.

He made the comments during a meeting with Ukraine's President Volodymr Zelenskyy on the sidelines of the United Nations General Assembly.

Asked if the U.S. would provide military backup, Trump said it “depends on the circumstance" but added, "we're very strong toward NATO."

NATO warned Russia on Tuesday that it would use all means to defend against any further breaches of its airspace after the downing earlier this month of Russian drones over Poland and Estonia’s report of an intrusion by Russian fighter jets last week.

The U.S. president also praised Zelenskyy in his nation's war against Russia, saying it's "putting up one hell of a fight."

"That's not a good thing for Russia," the president added. "Russia doesn't look very distinguished having taken three-and-a-half years...of very hard fighting. And it looks like it's not going to end for a long time."