WASHINGTON (JTA) — President Donald Trump warned Iran not to restart its nuclear weapons program should Trump pull out of the 2015 Iran nuclear deal, saying the country would have “big problems” if it followed that course.

Trump met Tuesday at the White House with President Emmanuel Macron of France and the deal was high on their agenda. Macron, like the other parties to the deal except for the Trump administration, favors keeping the agreement, which swaps sanctions relief for a rollback in Iran’s nuclear program.

Trump must decide by May 12 whether to continue waiving Iran sanctions, a key provision of the pact. If he does not, the deal risks collapse, and top Iranian officials say they would resume enriching fissile material at levels that were banned. Iran denies it is seeking a nuclear weapon.

Asked about the Iranian warnings, Trump said, “They’re not going to be restarting anything. If they restart it, they’re going to have big problems, bigger than they ever had before. And you can mark it down. If they restart their nuclear program, they will have bigger problems than they ever had before.”

With Macron present, Trump derided the deal, as he has many times in the past.

“It’s insane. It’s ridiculous. It should never have been made,” the U.S. leader said. “But we will be talking about it.”

After a break in their meeting, Macron and Trump again chatted with reporters, and they seemed closer on the Iran issue. France and others have offered to toughen sanctions on Iran on non-nuclear issues — for instance, its missile testing — as a means of keeping Trump invested in the deal.

“We’re looking forward to doing something,” Macron said, “but it has to be done and it has to be done strongly.”

Regarding Iran, Trump said: “We’re fairly close to understanding each other. Our one on one went very well.”