European powers have formally put the Iran nuclear deal in dispute.
France, Britain, and Germany triggered a mechanism on Tuesday (January 14) that amounts to accusing Iran of violating the deal's terms.
And could lead to "snapback" -- a return to the U.N. sanctions that were lifted in 2015 when the agreement was signed.
It's the strongest step the three have taken to enforce it.
They said they wanted to prevent a nuclear proliferation crisis adding to the escalating stand-off between Tehran and Washington, which peaked with the killing of Iran's top military commander, Qassem Suleimani, on January 3rd.
Iran's foreign ministry condemned what it called a passive action, and said it would support any act of goodwill to save the deal.
The nuclear deal requires Iran to curb its nuclear program, which it has always insisted is peaceful.
But U.S. president Donald Trump pulled the United States out in 2018, saying it was too weak.
It has ramped up sanctions that are severely damaging Iran's economy.
Since then, Iran has reduced its compliance, saying the Trump administration's actions give it the right.
Earlier this month it said it would scrap all limits on its uranium enrichment, but keep cooperating with the U.N. nuclear watchdog.
The question is now whether the European powers' step is a nail in the deal's coffin.
One man who seems to think so is Boris Johnson.
Britain's prime minister is calling for it to be scrapped and replaced with a new, quote, "Trump deal."
The EU, which acts as guarantor and must now inform fellow signatories Russia, China, and Iran itself, said it wanted a return to compliance, not to sanctions.