Soviet Premier Khrushchev and President John Kennedy at Soviet Embassy in Vienna on June 4, 1961. (AP)

President Obama, speaking at the Bush presidential library dedication Thursday, talked about how no one comes to the Oval Office fully aware of just how tough the job is.

Obama, in closing, recounted a story about former President John F. Kennedy confronting Soviet leader Nikita Khrushchev.

“On the flight back from Russia, after negotiating with Nikita Khrushchev at the height of the Cold War,” Obama began, talking about a slip of paper Kennedy had carried in his pocket with a favorite saying on it.

Okay. We recall Kennedy got brutally pounded — and he knew it — by the wily commie. But maybe Kennedy got more disoriented than anyone knew and took a most circuitous route back to Washington?

After all, the only summit Kennedy and Khrushchev had was not in Russia (or the Soviet Union as it was known) but in Vienna, Austria, in June 1961. (And he directly flew home via London, stopping to see the Queen, writes historian Michael Beschloss in his book “The Crisis Years: Kennedy and Khrushchev.”)

Okay, so that happened just before Obama was born. But he was nearly eleven when President Nixon made his historic trip to Moscow in May 1972, the first time an American president had gone to the Soviet capital.

What was that old song by the great Sam Cooke ? “Don’t know much about history . . .”