Announcing new sanctions on 14 Iranian entities and individuals, he added: “No one should doubt my word.” Although the president does not always follow through with his threats, he has nonetheless caused a flurry of diplomatic activity.

They have good reason; international inspectors have repeatedly confirmed Iran is complying with the agreement, which involves Tehran destroying or dismantling most of its nuclear infrastructure in exchange for the lifting of most economic and banking sanctions. Given the years of tough bargaining involved in the agreement and Tehran’s compliance, Iran understandably has refused to reopen talks.

Trump reluctantly renews Iran nuclear deal – for the last time

Trump wants a new deal drawn up that makes some of the pact’s terms permanent, including Iran’s ballistic missile programme, its support of extremist groups in the Middle East, and human rights. Pragmatism by his predecessor, who focused only on the nuclear issue, sealed the accord. 

Tying in matters that should be dealt with separately will bog down negotiations and destroy a rare success in the battle against nuclear proliferation. The American leader has another decision on the pact in four months; to do anything other than again waive sanctions will send the worst of messages.