WATCH: Trump attacks Biden on wars in Ukraine and Afghanistan

The questioning during Thursday’s CNN Presidential Debate turned to foreign policy beginning with the Russian war in Ukraine, which is now in its third year.

Former President Donald Trump suggested Russia never would have attacked Ukraine if he had been in office.

“If we had a real president, a president that knew that was respected by Putin, he would have never he would have never invaded Ukraine,” he said. Trump also attacked Biden on the withdrawal of U.S. forces from Afghanistan and on his stance on Iran.

WATCH: Biden and Trump debate — PBS News simulcast of CNN’s 2024 Presidential Debate

Trump has a long history of positive comments about Russian President Vladimir Putin’s toughness, including calling Putin’s tactics in the 2022 invasion of Ukraine “genius” and “very savvy.”

Trump expresses no such warmth for Ukraine or Ukrainian President Volodymyr Zelenskyy, most recently calling him a “salesman” this month for the Ukrainian leader’s military aid requests to the United States.

Joe Biden pushed back at Donald Trump bragging about pushing European allies to put more money into defense. “This is a guy who wants to pull out of NATO,” Biden said, adding that he “got 50 other nations” to support Ukraine against Russia’s invasion.

Biden forcefully responded to Trump’s NATO comments, saying: “He has no idea what the hell he’s talking about.”

About 6 in 10 Americans see NATO membership as a very or somewhat good thing for the U.S., while about one-quarter say it’s neither good nor bad and only about 1 in 10 say it’s very or somewhat bad, according to an AP-NORC poll conducted in February.