Hosting French President Emmanuel Macron in the Oval Office, Trump punctured a carefully choreographed display of trans-Atlantic camaraderie with an angry tirade against the three-year old nuclear accord.

The US leader groused that the agreement -- inked by the United States, Iran, Europe, Russia and China -- does nothing to tackle Tehran's ballistic missiles program or support for militant groups across the Middle East.

"People know my views on the Iran deal. It was a terrible deal. It should have never ever been made," Trump railed. "It's insane. It's ridiculous."

The agreement, still backed by Europe, gave Iran massive sanctions relief and the guarantee of a civilian nuclear program in return for curbs on programs that could be used to develop a nuke.

It did not tackle western complains about Iran's ballistic missile programs or support for militant groups across the Middle East.

Trump faces a May 12 deadline to decide on the fate of the accord and is demanding changes that European capitals believe would represent a legal breach.

Iran, meanwhile, has warned it will ramp up enrichment activities if Trump walks away from the accord, prompting Trump to issue a blunt warning.

"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," he said.

Macron is visiting Washington, in part, to convince Trump not to walk away from the deal and scuttle years-worth of hard won diplomatic gains.

"The Iran deal is an important issue but we have to take a far broader picture which is security in the overall region," he said Tuesday at the White House.

"What we want to do is to contain Iran and its presence in the region."

For months American and European officials have been working behind the scenes to trying to find a compromise over Trump's demands to change the agreement.

Officials have toyed with the idea of a separate joint declaration: promising to tackle non-nuclear issues, while searching for a tougher successor agreement.

The challenge, they say, is to find a solution that allows the mercurial US president to claim a public victory, while keeping the deal intact.

More hawkish American officials accuse Europeans -- particularly Germany -- of putting business interests ahead of security, and of opposing a tougher stance against Iran to safeguard investments in the Islamic Republic.