What did Donald Trump do today?

He changed his mind about negotiating with Iran over nuclear weapons.

Trump threatened Iran with an attack if it didn't abandon its nuclear weapons program. That is nothing new—Trump has been rattling his saber over Iran since his first term. But he also said that he would be willing to negotiate directly with Iran over its nuclear weapons program.

This marks a drastic change in tactics for Trump. Iran had been part of a multinational agreement with the United States and five other nations known as the Joint Comprehensive Plan of Action, or JCPOA. Under that arrangement, Iran halted development of its weapons program in exchange for sanctions relief. The other five nations—the U.S., China, Russia, Germany, France, and the U.K.—had the ability to monitor Iran's domestic nuclear energy program from inside the country.

In spite of Iran's compliance and the satisfaction of on-site monitors that it had effectively given up its ability to create the highly enriched uranium necessary for a nuclear weapon, Trump abrogated that treaty in 2018 and reimposed sanctions. Iran responded by resuming its enrichment of uranium and rebuilding its capacity to make weapons-grade material on short notice.

Trump never gave an explanation for his decision to blow up the agreement, other than his unsubstantiated belief that it was somehow a "bad deal," and his open contempt for the Obama administration. (Trump appears to genuinely believe, all evidence to the contrary, that he is a master tactician at the negotiating table.) 

Bad deal or not, the absence of a deal means that Iran can now effectively create the fuel for nuclear weapons at will, assuming it hasn't already.

At a press conference today, Trump was asked the obvious question: how would his proposed diplomatic solution differ from the JCPOA he had rejected? He appeared unsure as to what the reporter was referring to, and evaded the question.

Why does this matter?

• If you are constantly in a worse position as a result of your "dealmaking," you are a bad dealmaker.

• It's bad if a president can't remember major events from his first term, even if they happened seven years ago.