EU foreign affairs chief Federica Mogherini, who met privately with Secretary of State Mike Pompeo on Monday, said EU member states continued "to fully support the nuclear deal with Iran."

Washington has increased its pressure on the European Union to isolate Iran internationally and walk away from the 2015 nuclear deal.

Read more: Iran nuclear-deal crisis: Is war with the US ahead?

What was said

The German, French and British foreign ministers gathered to discuss the state of the Iran nuclear deal in Brussels.

Pompeo held talks with his counterparts on the sidelines of the summit.

Mogherini said the EU had called on Pompeo and the US to show restraint at a crucial moment in dealing with Iran.

German Foreign Minister Heiko Maas said he had again told Pompeo that Berlin did not want a military escalation.

Maas also stressed that in Europe's view, the pact was the best way to prevent Iran from building an atomic bomb.

British Foreign Secretary Jeremy Hunt said the UK was worried about the risk of accidental conflict between Iran and the US.

Read more: US military flare-up 'would be a godsend to Iran hard-liners'

'Joint effort'

Holly Dagres, non-resident fellow at the Washington-based Atlantic Council, told DW that the EU's options were limited when it comes to preserving the nuclear deal.

"The one thing that the EU could do right now is stand up against the Trump administration," Dagres said. "But the reality is that Europe is limited in terms of telling its companies to go and do business in Iran. These multinational companies don't want to because they're afraid of being sanctioned."

But she noted that the deal stands a chance if a joint effort is made along with other signatories of the agreement, including China and Russia.

"It should've been Britain, France, Germany and the EU coming out firmly against the Trump administration a year ago when they pulled out of the multilateral agreement. Now they still can. When there's a joint effort, there is strength in numbers versus if a single country is taking a stance to save the accord," said Dagres.

Read more: Opinion: US-Iran escalation a threat, but war unlikely

Rising tensions in the Gulf

Since last week, the US has deployed an aircraft carrier, bombers, an assault ship and a Patriot missile battery to the Persian Gulf in a sign of escalating tensions in the region.

Over the past month, the US has taken an increasingly aggressive position against Tehran. It labeled Iran's Revolutionary Guard a terrorist group and ended all sanctions wavers on Iranian oil.

Frustrated by the EU's response to the unraveling of the nuclear deal, Iran announced last week that it would withdraw from "voluntary commitments" made in the 2015 accord.

While the EU rejected "any ultimatum" on the deal, it said Iran's announcements "are not a violation or withdrawal of the nuclear deal."

What is the Iran nuclear deal?

The nuclear deal was orchestrated by Germany, France, the UK, Russia, China and the US under former President Barack Obama's leadership and Iran in 2015. It provided a framework for Tehran to end its nuclear program in exchange for the international community dropping crippling sanctions.

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