© Adam J. Dewey/Getty Images/AnadoluFormer US President Donald Trump
Russia's intervention in Ukraine was triggered by the irresponsible and provocative rhetoric of US President Joe Biden and his administration about Kiev joining NATO, Donald Trump has said.

Trump, who is seeking a rematch with Biden for the presidency in November, made the comments during a conversation on foreign policy with 'All-In' podcast co-host David Sacks on Thursday.

"For 20 years, I heard that if Ukraine goes into NATO, it's a real problem for Russia. I've heard that for a long time. And I think that's really why this war started," Trump said.

The Republican presidential candidate pointed out that there had been no talk about armed conflict between Russia and Ukraine when he was in the White House, but as soon as Biden replaced him, things began to deteriorate.

"I thought that [Russian President Vladimir] Putin may be - well, look, he's a good negotiator, I thought he was going to be doing that for negotiation purposes," Trump said. "Then all of a sudden, they attacked, and I said, 'what's going on here?'"

According to the former president, one of the key issues was the rhetoric coming out of the White House.

"Biden was saying all of the wrong things. And one of the wrong things he was saying [was] 'no, Ukraine will go into NATO'," Trump said.

Sacks pointed out that in January 2022 or thereabouts, US Secretary of State Antony Blinken told Moscow that Ukraine would join NATO and that Washington thought it was OK to put nuclear weapons there. "So no wonder the Russians hit the roof," he noted.

"Well, let's say you were running Russia. You wouldn't be too happy," Trump replied. "And that's always been off the table. It's always been understood that that was a no-no," he added, addressing Kiev's potential NATO membership.

Floating the idea of Ukraine in NATO was "very provocative," Trump said. "And now it's even more provocative. I hear routinely they're now talking about Ukraine entering NATO. And now I hear France wants to go in and fight. Well, I wish them a lot of luck!"

Putin has specifically pointed to Western statements about Ukraine's possible membership in the US-led bloc as a security threat Moscow could not ignore. Ukraine's neutrality has been one of the non-negotiable Russian conditions for the conflict to end.

NATO has argued that its "open door" policy is essential and that no one had the right of veto over it, but also that its expansion eastward was not the cause of the conflict.

In an interview with Time magazine earlier this month, Biden claimed that the US is "the strongest nation" because of NATO expansion, and that he told Putin he would get "NATOization of Finland" instead of "the Finlandization of NATO" during their June 2021 summit in Switzerland.