Europe will look on Friday for ways to guide the United States and Iran away from open conflict, knowing that a miscalculation from either side could leave the bloc facing a war and a serious nuclear proliferation crisis at its doorstep.
In a rare emergency meeting, EU foreign ministers, to be joined by NATO Secretary-General Jens Stoltenberg, may avoid any tough diplomatic response for now after Washington and Tehran backed off from an outright conflagration following the US killing of an Iranian general in Iraq and retaliatory missile strikes by Iran that avoided military casualties.
"Iran's desire to prevent the crisis from escalating has bought us some time, it has the effect of cooling this down just a little," a senior EU diplomat told Reuters.
But French Foreign Minister Jean-Yves Le Drian warned before the afternoon meeting that Iran could have a nuclear weapon in one to two years if the country fully breaks with a nuclear containment accord it reached with world powers in 2015.
"If they continue with unraveling the Vienna agreement, then yes, within a fairly short period of time, between one and two years, they could have access to a nuclear weapon, which is not an option," Le Drian said on RTL radio.
Iran has been gradually discarding the deal's limitations on its enrichment of uranium for nuclear fuel since President Donald Trump withdrew the United States from the accord in 2018, demanding tougher curbs on Iran.
Iran said its steps away from the deal are reversible if Washington returns to it and lifts crippling sanctions that have throttled much of Tehran's lifeblood oil trade.
The simmering tensions have highlighted Europe's struggles to influence either side and play a mediating role with European powers Britain, France and Germany desperately trying to pressure Iran to stick to the nuclear pact.
They also want to convince Trump, who on Wednesday called on them to join him in withdrawing from the nuclear deal, that they are tough-minded allies who will not be deceived by Tehran.
Late on Thursday, the EU's top diplomat Josep Borrell spoke by telephone with US Secretary of State Mike Pompeo.
"We need to coordinate and maximize the effect everybody has in trying to de-escalate what the Iranians do, but it's the same for the Americans. What's most worrying is a miscalculation," said a French diplomatic source.
Iran's decision on Monday to scrap all enrichment curbs has also left the European powers in an awkward position.
Iran has repeatedly denied its nuclear program has military rather than civilian ends. But it has already breached many of the deal's restrictions meant to increase the amount of time Tehran would need to accumulate enough fissile material for an atomic bomb from two to three months to about a year.
The latest announcements could start reducing that time and the three European powers - who along with Russia and China have attempted to salvage the deal since Trump's withdrawal - are keen to send a firm message that the breaches are unacceptable.
They have agreed to begin a dispute resolution process under the 2015 deal that could lead to renewed U.N. sanctions on Tehran, but have hesitated on the timing fearing Iran may react badly, given its current confrontation with Washington.
Despite its moves, Iran has said the United Nations nuclear watchdog, the IAEA, can continue its on-site inspections at its atomic sites, leaving some wiggle room for diplomacy.
"Iran has not set any targets or deadlines when it comes to uranium enrichment targets, so that gives us time," a second EU diplomat said. A third EU diplomat said the decision to launch the process had been made, but that Friday was unlikely.
"There is a concern that it could trigger an Iranian escalation," said a European diplomat.