Donald Trump pulled America out of the Iran nuclear deal on May 8, reimposing sanctions on the regime and delivering on an election campaign promise.
Iran has been accused of failing to be honest about its nuclear ambitions while supporting terrorist groups and acting in an increasingly hostile way across the Middle East.
Britain, France and Germany condemned the move in a joint statement and promised to stay within the nuclear agreement claiming that it was the only way to prevent a Middle-Eastern nuclear arms race.
However, the White House announcement was welcomed by Israel – which released new intelligence on Iran’s nuclear programme last week – and several Arab nations.
Mr Trump said: “It is clear to me that we cannot prevent an Iranian nuclear bomb under the decaying and rotten structure of the current agreement.
“The Iran deal is defective at its core. If we do nothing, we know exactly what will happen.
“In just a short period of time the world’s leading state sponsor of terror will be on the cusp of acquiring the world’s most dangerous weapon.
“Therefore I am announcing today that he United States will withdraw from the Iran nuclear deal.”
The US president added: “Any nation that helps Iran in its quest for nuclear weapons could also be strongly sanctioned by the United States.”
Hassan Rouhani, the Iranian president, warned that if negotiations with other partners to the deal failed then the country’s uranium programme will restart.
Shortly after the announcement, there were widespread reports of an explosion in Syria, possibly the result of an Israeli strike on Iranian forces.
The decision to reimpose sanctions raises fears that European companies who trade with the Iranian government and do business in America could be hit with sanctions.
Mr Trump has long been a critic of the Iran nuclear deal, which was signed by his predecessor Barack Obama and lifted sanctions in turn for the country’s nuclear programme being curbed. Mr Obama criticised the decision last night as a “mistake”.
Mr Trump said he was open to striking a new, wider deal with Iran that would address behaviour such as the country’s ballistic missiles programme and involvement in Syria and Yemen.
The US president said he wanted “real, comprehensive and lasting solution” that would thwart Iran’s nuclear ambitions.
He also made clear he was delivering on a 2016 election campaign pledge, saying: “The United States no longer makes empty threats. When I make promises, I keep them.”
The re-imposition of sanctions will come into effect between three and six months from now. It includes sanctions on Iranian oil exports, the country’s central bank, and Iranian businesses.
European companies with significant presences in the US could be caught up if they do not curtail business in Iran before the sanctions come into effect.
Some of them were exploring ways to continue doing business in Iran after making significant investments following the announcement of the nuclear deal three years ago.
The UK, France and Germany issued a joint statement saying they “regret” the decision and making clear they would remain in the agreement, known as the Joint Comprehensive Plan of Action.
The statement said: “Our governments remain committed to ensuring the agreement is upheld, and will work with all the remaining parties to the deal to ensure this remains the case including through ensuring the continuing economic benefits to the Iranian people that are linked to the agreement.”
It went on: “We encourage Iran to show restraint in response to the decision by the US; Iran must continue to meet its own obligations under the deal, cooperating fully and in a timely manner with IAEA inspection requirements.”
EU leaders are expected to meet within days to discuss how the deal can be rescued. Mr Rouhani, the president of Iran, said Iran would stay in the nuclear deal for now but was prepared to return to enriching uranium if its interests were not preserved.
He denounced Mr Trump’s speech as “psychological warfare” against Iran but said his country would not bow to pressure. “Our people have always been victorious in the face of conspiracies and we will also emerge victorious at this juncture.”
But he added in a warning: “I have ordered Iran’s atomic organisation that whenever it is needed, we will start enriching uranium more than before.”
Benjamin Netanyahu, the Israeli prime minister and a leading critic of the Iran deal, said Mr Trump had made a “brave and correct decision” to withdraw from the agreement.