Just six weeks after John F. Kennedy’s botched Bay of Pigs invasion, the U.S. president hurtled head-first into another disaster: his first and only summit with Soviet Premier Nikita Khrushchev.

“Worst thing in my life,” Kennedy told a New York Times reporter. “He savaged me.”

According to Richard Reeves, a journalism professor at the University of Southern California and author of President Kennedy: Profile of Power, the main problem was that Kennedy wasn’t properly prepared to take on the more experienced Khrushchev at the June 1961 summit in Vienna.

“He was the young guy and he wanted Khrushchev to believe that he was serious,” Reeves says of the 44-year old, who had been president for fewer than five months. Kennedy knew that Khrushchev likely saw him as a weak military leader for not seeing the Bay of Pigs invasion through, and he wanted to use his signature charisma to change his mind.

Yet despite Kennedy’s desire to be taken seriously, “he really didn’t listen closely to his own advisors,” Reeves says. “He had no real idea how tough it was going to be… He went in there unprepared and Khrushchev walked all over him.”

“This man is very inexperienced, even immature,” Khrushchev told his interpreter. “Compared to him, Eisenhower is a man of intelligence and vision.”

Kennedy ignored warnings from his advisors not to do things like, say, debate communist ideology with a 61-year-old Soviet. This got him stuck in time-wasting discussions about Marxism, where he was totally out of his league. Kennedy spent a lot of time defending aspects of the pre-World War II status quo, like British imperialism, that he didn’t actually want to defend.

The president also made admissions that played right into the premier’s hands. “Like Putin now, Khrushchev...wanted to be seen as equals with the United States,” Reeves says. To the horror of U.S. Joint Chiefs of Staff, Kennedy told the premier he considered Sino-Soviet forces and U.S.-Western European forces to be fairly equally balanced.

This disclosure “sent Khrushchev into near ecstasy,” writes Michael Beschloss in The Crisis Years: Kennedy and Khrushchev. “For the rest of his life he boasted that at this summit the leader of the United States had finally acknowledged that there was rough parity between the two great powers.”

Khrushchev’s aggression during the talks surprised Kennedy as well as Secretary of State Dean Rusk, who was shocked Khrushchev raised the possibility of war—something neither leader wanted.

According to a State Department memo, Khrushchev said that if the U.S. challenged the Soviet position in divided Berlin, the U.S.S.R. “must respond and it will respond,” eerily threatening that “It is up to the U.S. to decide whether there will be war or peace.” Kennedy reacted with a statement even more chilling: “Then, Mr. Chairman, there will be war. It will be a cold winter.”

The summit didn’t produce any concrete policy decisions, partly because the summit hadn’t had any set agenda or goals in the first place. Kennedy had gotten a pre-summit commitment from Khrushchev that they would discuss a nuclear test ban, but they weren’t actually able to agree on one.

After the talks, Kennedy told James “Scotty” Reston, a New York Times columnist, about how disappointed he was with how things had gone.

Khrushchev “thought that anyone who was so young and inexperienced as to get into that mess [i.e., the Bay of Pigs] could be taken,” the president said. “And anyone who got into it and didn’t see it through had no guts. So he just beat the hell out of me.” (Reston used Kennedy as an anonymous source in his article; he recorded these quotes in his notes.)

“I never met a man like this,” Kennedy remarked to another reporter, Hugh Sidey of Time magazine. “[I] talked about how a nuclear exchange would kill 70 million people in 10 minutes, and he just looked at me as if to say, ‘So what?’”

Obviously, Kennedy’s ego took a hit with this summit. But did it actually have a negative impact on U.S.-Soviet relations? Depends who you ask.

Two months after the summit, the Soviets erected the Berlin Wall. Frederick Kempe, president and CEO of the Atlantic Council, argues in his book Berlin 1961 that Kennedy could have prevented this if he were tougher on Khrushchev in Vienna.

Yet Reeves argues that the wall provided a compromise in Berlin for both the U.S. and the Soviet Union, and helped avoid a nuclear war over this issue. Therefore, the wall wasn’t something Kennedy was interested in preventing. Additionally, he thinks that the meeting, however rocky, helped establish a good relationship between the leaders. For Kennedy especially, it gave him a crash course on understanding Khrushchev.

“The meeting proved in the long run to be enormously valuable,” he says. “It was that relationship which led to things which, I would argue, kept the peace.” Though they never met in person again, Kennedy and Khrushchev continued to communicate and develop their relationship, with both coming to understand that neither wanted nuclear war.

That’s not to say Reeves thinks Kennedy would’ve repeated his Vienna mistakes if he’d had a second summit with Khrushchev. “John Kennedy read and studied history,” he says, and would have learned from the first experience that he needed to prepare.