President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE said Monday that Iran is "playing with fire" after it announced earlier in the day that it had exceeded the amount of low-enriched uranium it is allowed to stockpile under the Obama-era nuclear deal, from which Trump withdrew the U.S. last year.

"They know what they’re doing," Trump said during a bill signing in the Oval Office. "They know what they’re playing with, and they’re playing with fire. So no message to Iran whatsoever."

ADVERTISEMENT

The International Atomic Energy Agency, the group that monitors Iran’s compliance with the 2015 nuclear accord, confirmed Monday morning that Tehran has exceeded the stockpile limit.

Monday marked the first time Iran is known to have breached the terms of the deal.

Iran had agreed to cap its stockpile of low-enriched uranium at 300 kilograms, one of several restrictions on its nuclear activities, in exchange for the lifting of almost all international sanctions. Iranian officials said they are violating the terms of the deal because the U.S. withdrew and reimposed sanctions on Tehran.

The violation adds to long-simmering tensions between the U.S. and Iran, which have been on the rise since Trump pulled the U.S. out of the nuclear agreement last year. European allies, Russia and China have remained committed to the pact, formally known as the Joint Comprehensive Plan of Action.

Last-minute talks between Europe and Iran last week failed to convince Tehran to remain within the limits of the deal.

Trump spoke Monday with French President Emmanuel Macron Emmanuel Jean-Michel MacronNavalny released from hospital after suspected poisoning US-China tensions shadow United Nations meeting The US is missing an opportunity in Lebanon MORE about Iran exceeding the stockpile limit, the White House said.

The Trump administration has imposed numerous sanctions against Iran since pulling out of the nuclear deal, including on Tehran's oil sector, its precious metals sector and Supreme Leader Ayatollah Ali Khamenei and other high-ranking officials.

Observers worried that the two countries were headed for a military conflict after Iran shot down a U.S. surveillance drone last month. The two sides disputed whether the drone was in Iranian airspace at the time.

Trump later said he called off a retaliatory strike after learning it would lead to 150 Iranian casualties.