Paris - For more than a year, Europeans have balanced between Washington and Tehran as they sought to preserve the Iran nuclear deal, under pressure from both sides and trying to avoid angering either. But the next few days could be decisive as Europe desperately tries to hold the agreement together while Iran increasingly flouts it.
After Iran announced Monday that it had surpassed the 2015 accord's cap on uranium enrichment - the second breach of the agreement in a week - European diplomats gave themselves another week to encourage Tehran to come back into a compliance. French President Emmanuel Macron, who spent more than an hour on the phone on Saturday with Iranian President Hassan Rouhani, dispatched his top diplomatic adviser to Tehran to keep negotiating on Tuesday.
The European high-wire act could come to an end soon: France, Britain and Germany see higher levels of uranium enrichment as a red line that would leave them little alternative but to start the process of reimposing sanctions and ending the deal. Turning away international inspectors or installing more centrifuges would also be triggers for sanctions, diplomats said.
The Europeans - who have been battered by President Donald Trump for years about their low military spending - are also worried the United States could tear into their multinational companies or otherwise retaliate for continuing to do business with Iran.
But Europeans remain furious with the Trump administration for its unilateral pullout from the deal last year. They have little appetite to sign on to new sanctions, although they have even less interest in a nuclear Iran.
"We have called on Iran not to take further measures that undermine the nuclear deal," EU spokeswoman Maja Kocijancic said on Monday. "And we now strongly urge Iran to stop and reverse all activities that are inconsistent with the commitments made."
Europe is racing against the clock to save the agreement, which is known as the Joint Comprehensive Plan of Action, or JCPOA.
"The Europeans are trying to find the softest landing possible, before the dilemma scenario of a collapsed JCPOA and a potential U.S. or Israeli military strike on Iran is imminent," said Ellie Geranmayeh, an expert on Iranian nuclear proliferation at the European Council on Foreign Relations, a London-based think tank.
"Iran's actions so far have been very managed and calculated," Geranmayeh said. "On the spectrum of steps Iran could have taken, they're still on the low end of the spectrum."
"It wouldn't be pragmatic for the Europeans to suddenly pull the plug," she said.
And yet that is precisely what the United States has urged its European allies to do.
"If you're doing business in Iran, you never know if you're facilitating commerce or terrorism," Brian Hook, the U.S. Special Representative for Iran, said last month. "You can't do business with the United States and Iran. And everyone has chosen the United States over Iran for a number of reasons."
Vice President Mike Pence reiterated Monday the U.S. commitment to maintaining sanctions on Iran, saying that the Trump administration would "never allow Iran to obtain a nuclear weapon."
No European leader has invested as much energy into stabilizing the Iran situation as French President Emmanuel Macron, who lobbied Trump (unsuccessfully) to stick with the nuclear deal in the spring of 2018 and who was Europe's chief interlocutor over the weekend, as Tehran previewed its latest noncompliance measures.
In Macron's Saturday call with Rouhani, he attempted to persuade the Iranian leader that, along with European allies, he was still committed to the deal, the Elysee Palace said.
In the short run, the diplomacy made little difference. Iran said that it is now enriching uranium at 4.5 percent purity - far below the 90 percent needed for a nuclear weapon, or the 20 percent that some observers feared, but enough above the deal's 3.67 percent limit to signal its disgruntlement.
Europe doesn't want to overly antagonize the United States, since it depends on Washington for security from Russia and other threats. But Britain, France and Germany have poured months of effort into a complex bartering tool intended to shield some business deals.
To Iran's frustration, though, they have not yet managed any transactions. And now the Iranian announcements make it politically harder to launch the tool, known as Instex, since Europe does not want to reward bad behavior.
At the same time, European leaders are not in any rush to trigger a dispute resolution clause of the nuclear deal that could eventually lead to sanctions. They say the fact that Iran stayed bound to the agreement for more than a year after the United States pulled out is a sign that there still might be a way to salvage it.
That could change if Iran makes a dramatic break from the deal. Europeans say that then they would have little choice but to reimpose sanctions, lining up with the United States in unhappy harmony.
If the Europeans do formally flag Iran for violations, they would have about a month for further talks before any significant sanctions might be imposed.
"The fact is that we were hoping that by staying in middle position we would influence the Iranians and push them to be as reasonable as possible in the present context," said Dominique Moïsi, who advised the Macron campaign on foreign policy and who is currently a senior fellow at the Paris-based Institut Montaigne.
"And the Iranians have gone in the other direction, with the most radical elements becoming stronger in Iran thanks to Donald Trump's policy. In a way the risk of war is growing and our ability to prevent it is simply disappearing."
"There's no clear alternative, either," he said. "It's a line that doesn't work, but is there another line?"