I’ve written already about how Donald J. Trump belongs to an exclusive club. He’s one of six men alive today who’ve held the office of president of the United States.

He’s now in the midst of a potentially catastrophic international crisis involving North Korea and its budding nuclear weapons program.

Has the president called any of the five men who preceded him? Has he sought their counsel, their advice, their wisdom in how to handle this situation, or himself?

You can stop laughing now.

The 45th president’s non-relationship with the 44th president is most puzzling and troubling, although it shouldn’t be too surprising. Barack Obama sought to provide a smooth transition. Trump and Obama met for the first time in the Oval Office shortly after Trump’s election. Trump said they got along well. “I like him and I think he likes me,” Trump said.

It went downhill from there.

The president thinks highly of himself. He has great internal faith in his ability to solve any problem, quell any crisis that comes his way. The men who preceded him all were “losers.”

Trump’s presidential isolation goes against tradition. Imagine that.

John F. Kennedy sought Dwight Eisenhower’s counsel during the Cuban Missile Crisis of 1962. Harry Truman faced crises in Europe after World War II, so he called Herbert Hoover for advice. Obama had to help Haiti recover from a devastating earthquake, so he enlisted George W. Bush and Bill Clinton to assist in that effort.

The norm has been that these men rely on each other to provide advice and counsel that only they are qualified to provide.

The president won’t change his ways. That’s a given more than 200 days into his administration. It merely speaks to the arrogance of a know-nothing who has at his disposal the collective wisdom of individuals who faced their own share of crises — and who might have something of extreme value to pass on.

Donald Trump won’t listen.

To borrow a word: Sad.