NEW YORK  — “I have decided,” President Donald Trump declared Wednesday, announcing he’d reached a verdict on the Iran nuclear deal’s future even as top U.S. and Iranian officials headed into their highest-level talks of his presidency. Iran’s leader, meanwhile, lashed out at “ignorant, absurd and hateful rhetoric” in response to Trump’s blistering attack at the U.N.

The jabbing between Trump and Iran’s President Hassan Rouhani set the stage for a contentious meeting of the nuclear accord’s parties. Trump has sent strong signals that he could walk away from the seven-nation agreement, which would potentially lead to new U.S. sanctions on Iran and its international trading partners. The Iranians, in turn, have threatened to respond to any U.S. pullout by restarting nuclear activities that could take them closer to bomb-making capability.

Asked about his stance on the nuclear pact Wednesday, Trump said he had made a decision. Pressed for details, he replied coyly: “I’ll let you know.”

Shortly afterward, Vice President Mike Pence told the U.N. Security Council that Iran “continues to flout the spirit of the Iran deal, destabilizing the region and brazenly threatening the security of sovereign nations,” a toned-down version of the diatribe delivered by Trump in a General Assembly speech to fellow world leaders Tuesday.

It wasn’t clear if Trump had made a final decision to leave or stick with the Iran deal. On several other issues over his presidency, he has teased reporters with the idea that a major verdict might be imminent, only to delay announcements for weeks or months. Trump must next certify by Oct. 15 if Iran is complying with the deal, and officials have said Trump may use that occasion to declare Iran in violation.

In any event, the U.S.-Iranian exchanges augured poorly for Wednesday’s gathering of diplomats including Secretary of State Rex Tillerson and Iranian Foreign Minister Mohammad Javad Zarif. A year ago, such a get-together would have been considered routine as nations strove to implement an agreement that curtailed Iran’s nuclear activity in exchange for an end to various oil, trade and financial restrictions on the country. In the current environment, it is anything but ordinary.

Addressing the General Assembly, Rouhani said his country won’t be the first to violate the nuclear agreement, “but it will respond decisively to its violation by any party.” In a dismissive jab at Trump he said, “It will be a great pity if this agreement were to be destroyed by rogue newcomers to the world of politics.”

“By violating its international commitments, the new U.S. administration only destroys its own credibility and undermines international confidence in negotiating with it or accepting its word or promise,” Rouhani said. That echoes criticism even some of America’s allies have leveled at a time when the United States hopes to draw North Korea into a negotiation over its rapidly expanding nuclear arsenal.