Columnist

One person who obviously didn't know "what he was signing up for" is President Trump. Others include Trump voters who believed they were electing a decent human being to be commander in chief.

What Trump reportedly said to the grief-stricken widow of Sgt. La David T. Johnson, who gave his life for his country, is not some kind of minor miscue or media-fueled distraction. It speaks to the core issue of Trump's character and demonstrates, as clearly as any incident to date, his unfitness for the office he holds — and dishonors.

Johnson and three other U.S. soldiers — Staff Sgt. Jeremiah "J.W." Johnson, Staff Sgt. Bryan C. Black and Staff Sgt. Dustin M. Wright — were killed Oct. 4 in Niger, apparently ambushed by Islamic State-affiliated militants. Exactly what happened is unclear, and Congress should be as dogged in investigating these deaths as it was in probing Benghazi.

For 12 days, Trump said nothing, not even a tweet, about the four Americans killed in action, and had no contact with the loved ones they had left behind. Pressed by reporters to explain his silence, Trump reacted by slandering his predecessors, especially President Barack Obama, falsely claiming that they, too, neglected to console the families of the fallen.

Trump then placed a phone call to Myeshia Johnson, La David Johnson's widow. The truism "better late than never" is not always true.

According to two people who overheard the call, Trump told Johnson that her husband "knew what he was signing up for" although his death must still be painful. One witness who confirms these were Trump's words is the woman who raised Johnson as a son, Cowanda Jones-Johnson. The other is Rep. Frederica S. Wilson (D-Fla.) , who was with the family when Trump called. Wilson was so dumbfounded and angry that she quickly called Trump out publicly for what he had said.

Trump tweeted a denial and said he had "proof," but of course produced none. The president has shown himself to be such a liar that it's impossible to take his word over almost anyone else's.

Wilson was furious because instead of lessening Myeshia Johnson's grief, Trump had deepened it. Surely that was not his intent. But mindless cruelty is still cruel.

Offering succor to the families of service members killed in the line of duty is one of the most solemn exercises a president must undertake. It is a task requiring, above all, a sense of humility. "In the hope that it may be no intrusion upon the sacredness of your sorrow, I have ventured to address you this tribute to the memory of . . . your brave and early fallen child," Abraham Lincoln wrote to the parents of a deceased Union soldier.

Unlike true leaders, however, Trump seems to associate humility with weakness. When confronted with an error, big or small, he never just says, "I'm sorry, I made a mistake, I apologize," and leaves it at that. He always seeks to deflect responsibility. Somebody else is really at fault. Others who came before him have done worse. Bad people in the media are treating him unfairly.

Trump is a weak, narcissistic man in a job that requires strength and empathy. I'm not sure that empathy is a concept he even understands. He acts as if he believes that feeling someone else's pain is strictly for losers, not winners.

None of this is a surprise. We learned a lot about Trump during the campaign when he attacked the Khan family, who lost a son in Iraq, for having the temerity to criticize him politically. We have a president who believes that making the ultimate sacrifice for the nation is less important than supporting or opposing Trump.

The Post reported Wednesday that earlier this year, Trump phoned the father of Army Sgt. Dillon Baldridge, who was killed June 10 in Afghanistan. In the course of the conversation, Trump offered to send the father a personal check for $25,000 — but did not follow through. The check was finally sent this week only after The Post asked about it.

Sadly, that's typical Trump. He makes a grand promise, which allows him to feel big and generous — which is the whole point. Even in interactions with Gold Star families, it's all about him. Later, having played the role of Trump the Munificent, he forgets about it and goes in search of the next opportunity to shore up his fragile ego.

No one should expect him to grow in office. He's 71. At that age, either you have compassion, self-knowledge and a conscience, or you don't.

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