European countries said last week they wanted to preserve the Iran nuclear deal and rejected "ultimatums" from Tehran, after Iran relaxed restrictions on its nuclear program and threatened moves that might leave the worldwide pact.
"No-one wants Iran to come into possession of a nuclear bomb", German Foreign Minister Heiko Maas said as he arrived.
Karen Young, a resident scholar at the Washington-based American Enterprise Institute think-tank, said: "Tensions are high and have been escalated by the United States as well".
Hunt warned of the importance of ensuring that Iran doesn't resume banned atomic activities, saying that "if Iran becomes a nuclear power, its neighbors are likely to want to become nuclear powers".
At least one, British Foreign Secretary Jeremy Hunt, said he feared that unintentional escalation from the U.S. and Iran could spark a conflict - an unusually bold statement that appeared to assign equal culpability to Washington and Tehran. But he said it was clear Europe and the United States were "going about it in different ways ... taking different courses". "But the reality is that Europe is limited in terms of telling its companies to go and do business in Iran".
Venezuela is only one of a slew of issues where the United States and Russian Federation have clashed. "When there's a joint effort, there is strength in numbers versus if a single country is taking a stance against the United States".
Trump has sent an aircraft carrier and B-52 bombers to the Gulf in a show of force against what US officials have said is a threat to USA troops in the region.
As the USA sanctions bite, domestic pressure is increasing on Rouhani to demonstrate that Iran can still benefit from an agreement based on providing it with economic opportunities in exchange for limiting nuclear development. It labeled Iran's Revolutionary Guard a terrorist group and ended all sanctions wavers on Iranian oil.
This comes as Iran has given the five remaining parties to the nuclear deal a 60-day ultimatum to comply with their commitments, particularly those regarding Iran's economic interests in the banking and energy sectors, before the country would start reducing portions of its own commitments to the agreement stage by stage.
Iran responded by declaring it will scale back compliance with parts of the nuclear deal.
Trump's withdrawal from the 2015 Iran deal, which aims to prevent Tehran from developing nuclear weapons, is strongly opposed by Britain, France and Germany, the European signatories to the accord, which the EU helped to negotiate. It provided a framework for Iran to end its nuclear program in exchange for the global community dropping crippling sanctions.