The European Union Monday reaffirmed its support for the 2015 nuclear deal between Iran and world powers despite sharp criticism of the accord by US President Donald Trump. It also urged US lawmakers not to re-impose sanctions on Tehran. Trump defied both US allies and adversaries Friday by refusing to formally certify that Tehran is complying with the accord, even though international inspectors say it is, announcing that he might terminate the agreement. EU foreign ministers meeting in Luxembourg said failure to uphold an international agreement backed by the UN Security Council could have serious consequences for regional peace and also undermine efforts to check North Korea's nuclear ambitions. “As Europeans together, we are very worried that the decision of the US president could lead us back into military confrontation with Iran,” German Foreign Minister Sigmar Gabriel told reporters. After a closed-door meeting on Iran chaired by EU Foreign Policy Chief Federica Mogherini, EU ministers issued a joint statement saying the 2015 deal was key to preventing the global spread of nuclear weapons. “The EU is committed to the continued full and effective implementation of all parts of the JCPOA,” it said, referring to the Joint Comprehensive Plan of Action, the formal name of the accord with Iran agreed in July 2015 in Vienna. Trump meanwhile renewed his criticism of the accord, and raised the possibility he might try to end it completely. “We'll see what phase two is. Phase two might be positive, and it might be very negative. It might be a total termination. That's a very real possibility. Some would say that's a great possibility,” the US president said in Washington. He repeated his contention that the JCPOA was “a horrible deal for the United States”. EU foreign ministers said the accord was crucial to opening up Iran's $400-billion economy and finding a new market for European investors. Unlike the United States, the EU saw relations with Iran flourish in the late 1990s until revelations about Tehran's nuclear ambitions in 2002. “Non-proliferation is a major element of world security and rupturing that would be extremely damaging,” French Foreign Minister Jean-Yves Le Drian told reporters. “We hope that Congress does not put this accord in jeopardy.” Mogherini said she would travel to Washington early next month to try to muster support for the accord. The International Atomic Energy Agency (IAEA) says Iran is complying with its commitments under the accord, which Trump has branded “the worst deal ever negotiated.” The EU still has sanctions in place against members of Iran's Islamic Revolutionary Guard Corps, a major target of Trump's criticism. The EU ministers also discussed Monday Iran's ballistic missile programme, which they want to see dismantled. Negotiated after 12 years of talks, the accord with Iran was the most significant diplomatic success for the European bloc in several decades, and for former US president Barack Obama. Many worry that the EU's reputation as an honest broker in future conflicts may not recover if the US Congress re-imposes sanctions on Iran and causes the deal — which had the strong backing of Trump's predecessor, Obama — to unravel. Most UN and Western sanctions were lifted more than 18 months ago under the deal, though Tehran is still subject to a UN arms embargo, which is not part of the deal. EU foreign ministers also approved a new batch of economic sanctions on North Korea after its atomic test last month, including an oil embargo and investment ban. Meanwhile, Iranian Foreign Minister Mohammad Javad Zarif, who headed his country's negotiations team in the nuclear deal talks, said Sunday that Iran would adhere to the 2015 nuclear deal so long as European signatories also remain committed to the agreement. “The resistance of the Europeans (against the US) will show whether the nuclear agreement can be carried forward or not,” Zarif said. He was optimistic that European leaders would continue to support the deal given their geopolitical and economic interests in Iran. He also said an abiding commitment would also show “whether Europe could play its own role independent of the US in the world”. Zarif's comments echo those of Iranian President Hassan Rouhani who earlier said Iran would not withdraw from the agreement if the remaining signatories — the four UN Security Council members Russia, China, France and Britain plus Germany — also remained committed. British Prime Minister Theresa May and German Chancellor Angela Merkel on Sunday said their governments would not withdraw from the nuclear deal. During a phone call, “they agreed the UK and Germany both remained firmly committed to the deal”, a British government spokeswoman said. “They also agreed the international community needed to continue to come together to push back against Iran's destabilising regional activity, and to explore ways of addressing concerns about Iran's ballistic missile programme,” the spokeswoman added. On Saturday, Zarif said Trump's speech had violated the terms of the nuclear agreement. According to the Iranian minister, the US had not implemented the deal “in good faith” and had not “refrained from reintroducing or re-imposing” sanctions against Iran's nuclear programme. “I have already written nine letters [to EU foreign policy chief, Federica Mogherini] listing the cases where the United States has failed to act on or delayed its commitments under the JCPOA,” Zarif said. He warned that Tehran would respond to any new US sanctions with a “reciprocal measure”. The head of Iran's Atomic Energy Organisation (IAEA), Ali Akbar Salehi, on Saturday warned that Tehran would stop allowing unannounced UN nuclear inspections if the agreement fell apart. He said Iran's adherence to the Additional Protocol of the Non-Proliferation Treaty, which allows the IAEA inspections, would be “meaningless” without the wider agreement. He also warned that Iran would restart production of highly enriched uranium at 20 per cent if the US reintroduced sanctions, which he said the country could do “within four days”. Nuclear weapons require 90 per cent enriched uranium, but 20 per cent enriched uranium can be converted to 90 per cent in a short period of time. Analysts believe that, in effect, Trump has put the agreement in limbo without killing it off entirely as some backers had feared. But his strategy risks setting off a chain of unpredictable events that could end up derailing the deal anyway and eventually raise the risk of war between the US and Iran. Trump accused Iran of committing “multiple violations of the agreement”. He said that Iran had “failed to meet our expectations in its operations of advanced centrifuges,” and “intimidated” international inspectors into not using their full authority. He also accused the Obama administration of lifting sanctions on Iran under the terms of the deal at a moment when the Iranian clerical regime was about to collapse, an assessment that contradicts the views of many experts. He also ordered US intelligence agencies to mount a new assessment of Iran's compliance. The US president announced that he would no longer make regular certifications that the lifting of sanctions under the deal had been in US interests. “We cannot and will not make this certification. We will not continue down a path whose predictable conclusion is more violence, more terror and the very real threat of Iran's nuclear breakout,” he said. “I am directing my administration to work closely with Congress and our allies to address the deal's many serious flaws so that the Iranian regime can never threaten the world with nuclear weapons.” He said the deficiencies of the agreement included “sunset” provisions under which limits on Iran's nuclear programme will begin to expire. Proponents of the deal dispute that. Trump warned that the deal was plagued by “insufficient enforcement” and near total silence on Iran's missile programme. The Obama administration deliberately excluded other disagreements with Iran from the deal, reasoning that the greatest threat was Tehran being able to quickly race to a nuclear weapon in a matter of months. Trump warned that if he did not get the changes he wanted, he would unilaterally kill the deal. “In the event we are not able to reach a solution working with Congress and our allies, then the agreement will be terminated. It is under continuous review and our participation can be cancelled by me as president at any time.” The comment appeared to be a classic negotiating gambit by Trump, leaving other parties to the deal in no doubt that he is ready to walk out to get better terms. Given the deep reluctance of the Europeans, Russia and China and Iran to reopen the agreement, his approach is a high-risk one. Still, if he were to later back down, it would not be the first time that Trump has spelled out a tough stance and ultimately moderated his stand.