JERUSALEM — With time running out before the May 12 deadline by which President Trump is to decide whether to pull out of the Iran nuclear deal, the leaders of Israel and Iran weighed in on Sunday, with one calling the agreement “fatally flawed” and the other warning of “historic regret” if the United States rips up the deal.
Prime Minister Benjamin Netanyahu of Israel repeated his call for the agreement to be “fully fixed or fully nixed,” arguing that while it may have delayed the acquisition of Iran’s first bomb, it paves the way for the country to build an entire nuclear arsenal soon after the deal expires.
In Iran, President Hassan Rouhani, whose negotiating team reached the nuclear accord with six world powers in 2015, said the Trump administration would come to rue any decision to renounce the agreement.
“If America leaves the nuclear deal, this will entail historic regret for it,” Mr. Rouhani said in a speech broadcast live on state television. He warned in veiled terms that Iran could consider restarting its now largely mothballed nuclear energy program, which is under inspection of the International Atomic Energy Agency.
Mr. Rouhani added that there would be no negotiations on limiting Iran’s missile power or regional influence.
“Our nation honors its commitments, but it plainly tells the whole world, Europe, America, West and East: We will not negotiate our weapons and defense of our country with anybody,” Mr. Rouhani said. “What decision the Iranian nation has made for self-defense is nobody’s business.”
On top of Mr. Trump’s threats to exit the agreement, Mr. Rouhani faces several domestic problems. The country’s currency, the rial, has lost around 35 percent of its value since his re-election in May last year, and his popularity has slipped among the middle classes for having failed to achieve some of the economic and social changes he promised. His opponents in the military and clerical ranks have increased their political attacks against him.
Speaking to international reporters on Sunday, Mr. Netanyahu pushed back against critics who said a trove of pilfered Iranian documents he revealed last week had showed nothing new.
“Anyone who says there is nothing new in the material we showed has not seen the material,” Mr. Netanyahu said, days after exposing Israel’s acquisition of a huge archive of stolen Iranian nuclear plans, mostly relating to a covert bomb-making project that was halted in 2003.
Mr. Netanyahu said that the deal was “fatally flawed on weaponization,” referring to the military application of Iran’s enriched uranium, and that the documents proved it was based on a lie. He added that the cache of more than 100,000 pages was now being shared with the intelligence services of the countries who negotiated the agreement with Iran: the United States, Russia, China, France, Germany and Britain.
To those arguing that the documents did not prove any Iranian violation of the accord since it came into effect in 2016, Mr. Netanyahu said that was missing the point.
“If you don’t violate a dangerous deal, it doesn’t make it less dangerous,” he said, adding that the accord was based on “a fictitious Iranian report” to the International Atomic Energy Agency, in which Iran denied having ever planned to build a weapon.
Mr. Netanyahu also dismissed experts who said the documents just proved why a deal was necessary. “A deal that enables Iran to keep and hide all its nuclear weapons know-how is a horrible deal,” he said.
The accord gave Iran “unlimited enrichment in both ways,” he said, because it removed economic sanctions on Tehran and at the same time “gives them the ability to enrich uranium on an industrialized scale” when the restrictions in the deal end.
“The last thing you can say about it is that it blocks all of Iran’s paths to the bomb. In fact, it does the very opposite,” Mr. Netanyahu said. “If you do nothing to this deal, if you keep it as is, you will end up with Iran with a nuclear arsenal in a very short time.”
Mr. Netanyahu has staked his political career on blocking Iran and its nuclear ambitions, which pose a potential existential threat to Israel, but there is no sign so far that his campaign has shifted European leaders who have lobbied Mr. Trump not to scuttle the deal.
Many experts, including former Israeli security officials, have said that while the deal may be flawed, it is better than having no deal. The Israeli government argues for the re-imposition of economic sanctions on Tehran, which it says will serve to curb not only Iran’s nuclear ambitions, but also its power in the Middle East.
An Israeli intelligence official who briefed the foreign reporters, on the condition of anonymity in line with his agency’s rules, said that only a fraction of the stolen Iranian archive had been presented publicly. He added that 99 percent of it was new to Israel in the quantity and quality of information it provided about Iran’s military nuclear project.
Mr. Netanyahu said he would be meeting President Vladimir V. Putin of Russia on Wednesday in Moscow, amid escalating tensions over Iran’s efforts to entrench itself militarily in Syria. He warned that Israel would do all it could to thwart Iran’s efforts there, even if that meant entering into a conflict.
“In recent months, the Iranian Revolutionary Guards organization has transferred to Syria advanced weaponry in order to attack us both on the battlefield and on the home front,” Mr. Netanyahu said in remarks broadcast on Sunday. He said the weapons included drones, missiles and “antiaircraft batteries that would threaten air force jets.”
The remarks came as Israel braced for Iranian retaliation for an attack last month on an Iranian drone facility at an air base in Syria.
Isabel Kershner reported from Jerusalem, and Thomas Erdbrink from Tehran. David M. Halbfinger contributed reporting from Jerusalem.