Donald John Trump thinks he is operating in a free-fire zone.

Political foes are open targets for his insults. That’s a given.

But a former president? Of the current president’s own party?

The 45th president of the United States decided Thursday to denigrate the charitable program initiated by the 41st president of the United States. He told the rally crowd in Great Falls, Mont., that he didn’t understand George H.W. Bush’s “Thousand Points of Light” program, the one that called on Americans to help one another, apart from government.

“What the hell does that mean?” Trump asked.

Mr. President, it means charity. It means selflessness. It means public service in the purist sense of the term.

For this president to denigrate the work of a man — President Bush — who just buried his beloved wife of more than seven decades speaks volumes about his absolute callousness.

And I hasten to point out here that President Barack Obama honored President Bush when he awarded the 41st president the Presidential Medal of Freedom — the nation’s highest civilian honor — for the very work that Trump decided to disparage.

This is how you pay tribute to a great American:

Pay attention — for once in your life! — Mr. President.