By reneging on the Iran nuclear deal, President Trump has said, he will be able to get an even better deal, one that will also control Iran’s ballistic missiles and its regional influence.

Sound familiar? It should. This is the same kind of gesture toward a better, smarter deal that Mr. Trump made when he pulled the United States out of the Paris climate agreement, the same sort of empty promise he made in saying he would supply plans for Middle East peace and better, cheaper, more accessible health care. So far, again and again, he has shown himself to be adept at destroying agreements — a relatively easy task for a president — and utterly lacking in the policy depth or strategic vision and patience to create new ones.

When it comes to the danger of a nuclear arms race in the Middle East, there is no sign Iran or any of the other major powers in the existing and so far successful pact will simply fall in line with Mr. Trump’s notional new plan. More likely, his decision, announced on Tuesday, will allow Iran to resume a robust nuclear program, sour relations with close European allies, erode America’s credibility, lay conditions for a possible wider war in the Middle East and make it harder to reach a sound agreement with North Korea on its nuclear weapons program.

In other words, par for the course. This man who, apparently because of one book and a reality television show, has a reputation as a deal maker despite a skein of bankruptcies and lawsuits, has been piling up quite a record of scuttled agreements that he suggests “never, ever should have been made” and broken promises for a “better deal.”