Under the accord, reached in 2015, Iran agreed to curb its nuclear program in exchange for the lifting of international sanctions. Under United States law, Mr. Trump has until Oct. 15 to certify whether Iran is complying, and while he has done so twice since taking office, he has signaled that he will refuse to do so again.
That by itself would not abrogate the deal, but would give Congress 60 days to reimpose sanctions on Iran, an action that would mean an end to the agreement, at least for the United States.
Mr. Trump may see decertification, or the threat of it, as leverage to press Iran and the other powers to restart talks. He could offer to certify for another 90 days if other parties agreed to explore new negotiations.
On Wednesday, he teased reporters who asked him whether he had decided what to do. “I have decided,” he said, repeating the phrase three times. Pressed by reporters, he added: “I’ll let you know. I’ll let you know.”
Secretary of State Rex W. Tillerson seemed to foreshadow the strategy in a television interview on Tuesday. “The president really wants to redo that deal,” he told Fox News. “We do need the support, I think, of our allies, the European allies and others, to make the case as well to Iran that this deal really has to be revisited.”
Two provisions he and others focused on involve the expiration of the agreement and its failure to stop Iran from developing ballistic missiles. Under the deal, sealed in 2015, some provisions expire, or “sunset,” after as little as 10 years while others are in force longer and some are permanent. And although United Nations provisions seek to limit ballistic missile technology, the nuclear agreement does not prohibit Iran from developing such weapons on its own.
“If we’re going to stick with the Iran deal, there has to be changes made to it,” Mr. Tillerson said. “The sunset provision simply is not a sensible way forward. It’s just simply, as I say, kicking the can down the road again for someone in the future to have to deal with.”
The other five major powers that negotiated the agreement along with President Barack Obama — Britain, France, Germany, Russia and China — have resisted any effort by Mr. Trump to simply tear it up. But President Emmanuel Macron of France opened the door to rethinking its terms on Wednesday, two days after meeting with Mr. Trump.
Speaking to reporters outside the United Nations Security…