The collapse of the Iran nuclear deal will leave the world a much more dangerous place, drastically weakening the chances of an accommodation with North Korea, and raising the spectre of violent conflicts breaking out, John Kerry has warned.

The former US Secretary of State has been meeting European leaders in an a concerted attempt to save the landmark agreement in the face of Donald Trump’s threats to tear it up. The President has been claiming, against all evidence, that Tehran was not fulfilling its side of the bargain and has failed to uphold the “spirit” of the deal.

The crisis comes at a particularly volatile time in the Middle East; with Saudi Arabia in a state of flux with mass arrests, including members of the royal family, rockets being fired into the Kingdom from Yemen, and the Prime Minister of Lebanon, Saad Hariri, resigning because, he claims, he feared for his life while the Saudis and Iranians accused each other of destabilising the country.

Mr Kerry, who played a key role in securing the accord between Iran and international powers, said: “It is important to note the simple things, the Iran nuclear deal is working, it is doing precisely what it was set up to do. President Trump’s decision to decertify the Iran deal made no reference to any fact whatsoever. The IAEA (International Atomic Energy Authority) has confirmed Iran’s compliance no less than eight times.

“I heard Mr Trump say there’s a violation of the spirit of the Iran deal. There is no spirit of the deal. What we have is a deal focused on the nuclear questions. And it is delivering. The idea of violation has simply been pulled out of the sky, there is no scientific bases, no evidence that would demerit certification.”

Mr Kerry, who served with distinction in Vietnam with the US Navy, receiving the Silver Star, Bronze Star and three Purple Hearts, stressed the need to ensure that peace prevails. Mr Trump, a Vietnam draft dodger, has repeatedly threatened war on those he considers to be America’s enemies.

Touching the Remembrance Day poppy on the lapel of his jacket, Mr Kerry stated: “We wear these for a reason. We wear these to remind us of the need to exhaust all diplomatic efforts. We wear these to remember how mistakes, stupidity and absurdity can lead to so many deaths.”

Speaking at the Chatham House think tank in London, the former Secretary of State recalled how the Israeli Prime Minister, Benjamin Netanyahu, urged Barack Obama to bomb Iran. “After you bomb a country you give them reason to want a weapon. The Iran deal makes Israel safer, the security people in Israel know that. Bombing Iran would not have stopped Iran developing a bomb, the deal does.”

Mr Kerry continued: “We all know what the world would have looked like without a deal with Iran. We knew Iran was maybe two months from a nuclear break-out. Under the deal we have cradle to grave visibility on every ounce of uranium, the situation has never been more transparent.”

The world with the deal falling apart, he held, “would not look so good”. Tehran acquiring nuclear weaponry, he said, will have a ripple effect “with a nuclear arms race in the Middle East” further destabilising an already volatile region and have wider consequences. The agreement “acts as an example to North Korea and ensures the region is safer. Throwing it away would undermine US credibility,” he said.

The British diplomat Baroness Cathy Ashton, the High Representative of the European Union for Foreign Affairs and Security Policy, also a leading player in the Iran negotiations, recalled: “The North Koreans were always interested in the Iran negotiations, they used to turn up to where the meetings were being held. If the US pulls out now it will send a message to the world that it cannot keep to its commitments.”

Baroness Ashton pointed out the sheer effort that took place under extremely difficult circumstances, often with the international powers locked in confrontation between themselves while presenting a united front to Iran. “Russia backed sanctions on Iran when we were sanctioning Russia on Ukraine”, she noted.

Mr Kerry commented that it was crucial that Russia and China are kept on board rather than being distanced by the US jettisoning the deal. “Russia has never got enough credit for the 30 million people who died fighting fascism in the Second World War”. Vladimir Putin, he added, had an important role to perform in countering instability.