President Trump held a bilateral meeting with the President of the European Commission, Ursula von der Leyen, during which she was asked how soon she believes Europe could stop buying oil from Russia.

“President Trump is absolutely right on it," she said. "We have reduced already massively the gas supply from Russia, completely gotten out of Russian coal and massively also reduced the oil supply. But there's still some coming to the European continent."

"We want to get rid of it," she said, adding that Europe "absolutely" wants to stop purchasing Russian energy before her previously stated target date of 2027.

-ABC News' Hannah Demissie

President Trump was asked during his bilateral meeting with Ukrainian President Volodymyr Zelenskyy if he thinks NATO countries should shoot down Russian aircraft if they enter their airspace.

"Yes I do," Trump said.

Pressed on whether the U.S. would back up NATO allies in such a situation, Trump said it "depends on the circumstance."

Poland and now Estonia have reported violations of their airspace by Russian aircraft. NATO's Secretary General Mark Rutte reaffirmed the group's commitment to defend allied territory earlier Tuesday after most recent incursion in Estonia, but stopped short of saying Russian aircraft would be shot down if it happened again.

President Trump and Ukrainian President Volodymyr Zelenskyy are meeting on the sidelines of the United Nations General Assembly.

Trump called Zelenskyy a "brave man" and said he has "great respect for the fight" Ukrainians are engaged in. Zelenskyy thanked Trump for his efforts to bring an end to the war.

The Ukrainian president said he would speak to Trump on what's happening on the battlefield, how to finish the war and the issue of security guarantees. Zelenskyy called for greater pressure on Russia and said he supports Trump's call for European countries to stop buying Russian oil.

President Trump is calling off a meeting with top congressional Democrats, saying it would not be productive as he believes their government funding proposal is "unserious and ridiculous."

"After reviewing the details of the unserious and ridiculous demands being made by the Minority Radical Left Democrats in return for their Votes to keep our thriving Country open, I have decided that no meeting with their Congressional Leaders could possibly be productive," Trump wrote in a post on his social media platform.

Trump called off the meeting just hours after Democratic leaders Chuck Schumer and Hakeem Jeffries celebrated the meeting confirmation and addressed what they planned to press Trump on during the gathering.

Jeffries' office said he plans on addressing the cancellation at a 2 p.m. news conference.

The development comes as the Sept. 30 funding deadline inches closer with no clear path forward to avoid a shutdown.

-ABC News' Lalee Ibssa