UNITED NATIONS — Iran fired back sharply at President Donald Trump at the United Nations on Wednesday, dismissing what it called “ignorant, hateful and absurd rhetoric” and challenging his threats to tear up the 2015 nuclear deal with Iran.

A day after Trump denounced Tehran as a “rogue state” to the U.N. General Assembly, Iranian President Hassan Rouhani stood before the same gathering of global leaders and diplomats, and aimed the insult back at him.

“It would be a great pity if this agreement were to be destroyed by rogue newcomers to the world of politics,” Rouhani said of the nuclear accord.

The disarmament deal “belongs to the international community in its entirety, and not only to one or two” governments, he said.

President Barack Obama had argued that the U.N.-approved accord would destroy Iran’s ability to build nuclear weapons in exchange for lifting economic sanctions. Over the last two years, the International Atomic Energy Agency, the U.N. nuclear watchdog agency, has repeatedly found Iran is complying with the pact.

But Obama also hoped that easing sanctions would draw Iran more into global trade and other systems, ending more than three decades of enmity and isolation, much as China has emerged as a major power.

The latest bitter tit-for-tat at the U.N. lectern shows how U.S.-Iranian relations remain as estranged as ever, with both sides leveling angry charges on the global stage. It comes as Trump simultaneously is trying to convince North Korea to give up its nuclear arms through negotiations or face annihilation.

Trump said Wednesday he has made a decision on whether he will certify to Congress by an Oct. 15 deadline that Iran is complying with the nuclear deal, as he already has done twice this year. But he refused to say what he has decided.

“I have decided,” Trump said three times in response to shouted questions from reporters before he met with Palestinian Authority President Mahmoud Abbas at a hotel near the U.N. When pressed further, he smiled and said, “I’ll let you know.”

As recently as Tuesday, administration officials were preparing options for Trump to consider before next month’s deadline. As a candidate he had vowed to abandon the deal, but Secretary of State Rex Tillerson conceded this weekend that Iran is in “technical compliance.”

Senior White House aides are divided on whether to pull out of the agreement or stay in it for fear that withdrawal would cause deep divisions with U.S. allies, and potentially allow Iran to resume the very nuclear program it was designed to stop.

Several of Trump’s close advisers have tried to convince him to stay for now to give them time to work with allies to toughen some terms of the agreement.

French President Emmanuel Macron in particular has been working with other European leaders on adding additional measures. He said he had urged Trump in a meeting Monday to stay in the deal.

“I don’t understand what the substitute plan is,” Macron told reporters Tuesday. “If we simply throw away this agreement we can’t replace it.”

If Trump withholds certification — which he has hinted strongly he will — Congress will have 60 days to decide if U.S. sanctions related to Iran’s nuclear program should be put back in place.

That would effectively end the U.S. side of the deal. It’s less clear if it would destroy the accord since it also was negotiated by France, England, Russia, China and Germany, and none of those governments supports ripping it up.

Trump excoriated Iran in his debut address to the General Assembly on Tuesday.

“The Iranian government masks a corrupt dictatorship behind the false guise of a democracy,” he said. He called it “an economically depleted rogue state whose chief exports are violence, bloodshed and violence.”

He accused Iran of supporting militants in Syria, Yemen and Lebanon, expanding its ballistic missile programs, and pursuing “death and destruction” in the Middle East.

“We cannot let a murderous regime continue these destabilizing activities while building dangerous missiles,” he said. “And we cannot abide by an agreement if it provides cover for the eventual construction of a nuclear program.”

He all but called for regime change in Tehran, saying “the good people of Iran want change and, other than the vast military power of the United States, Iran’s people are what their leaders fear the most.”

Rouhani also minced no words in his address Wednesday.

Without mentioning Trump by name, the Iranian leader decried “ignorant, absurd and hateful rhetoric” delivered in the chamber a day earlier.

He singled out “the new U.S. administration” in saying it would destroy its own credibility by abrogating international agreements.

Rouhani, who won a second presidential term earlier this year, said Iran would not be the first to violate the agreement, but that it would take unspecified steps if others did so.

“We never threaten anyone, but we do not tolerate threats from anyone,” he said. “We believe in dialogue based on equal footing and mutual respect.”

Trump also used his U.N. speech to threaten to “totally destroy” North Korea if an attack is warranted, and again mocked its leader Kim Jong Un as “Rocket Man on a suicide mission for himself and his regime.”

At the Pentagon, asked about Trump’s “Rocket Man” comment, Defense Secretary Jim Mattis emphasized diplomacy.

“We are dealing with the North Korea situation through the international process, and we will continue to do so,” Mattis told reporters. “Secretary (of State Rex) Tillerson is leading the effort, and we will hopefully get this resolved through diplomatic means.”