WASHINGTON • Iran has exceeded a key limitation on how much nuclear fuel it can possess under the 2015 international pact curbing its nuclear programme, effectively declaring that it would no longer respect an agreement that US President Donald Trump abandoned more than a year ago.

Iranian Foreign Minister Javad Zarif confirmed yesterday that the limit had been breached, and the ministry's spokesman Abbas Mousavi said steps to decrease the country's commitments to the nuclear deal were "reversible".

The International Atomic Energy Agency (IAEA) said its inspectors were verifying whether Iran had accumulated more enriched uranium than allowed.

The breach of the limitation, which restricted Iran's stockpile of low-enriched uranium to about 300kg, does not by itself give the country enough to produce a nuclear weapon.

But it signals that Iran may be willing to abandon the limits and restore the far larger stockpile that took the United States and five other nations years to persuade Teheran to send abroad.

Mr Joseph Cohen, head of the Israeli intelligence agency Mossad, urged the international community to stop Iran from "stepping up enrichment".

"Just imagine what will happen if the material stockpiled by the Iranians becomes fissionable, at military enrichment grade, and then an actual bomb," he told the Herzliya security conference before Mr Zarif's announcement. "The Middle East, and then the entire world, will be a different place. Therefore, the world must not allow this to happen."

It was unclear how much the action would escalate the tensions between Washington and Teheran after the downing of a US surveillance drone by Iran last month nearly resulted in military strikes.

While the Trump administration had no immediate reaction to the announcement, Secretary of State Mike Pompeo last month said the US would never allow Iran to get within one year of possessing enough fuel to produce a nuclear weapon.

A senior Iranian parliamentarian yesterday said Israel will be destroyed in half an hour if the US were to attack. "If the US attacks us, only half an hour will remain of Israel's lifespan," Mr Mojtaba Zolnour, chairman of the Iranian Parliament's National Security and Foreign Policy Commission said, according to the semi-official Mehr News Agency.

For now, however, Iran seems to be on a pathway to step-by-step dissolution of key parts of the accord. Iranian President Hassan Rouhani has said that the country will begin raising the level of uranium enrichment this month.

It is possible that exceeding the stockpile limit is largely a negotiating tactic, a way for Teheran to impose costs on Washington after enduring more than a year of sanctions.

But the move is risky. Even before the announcement, the Pentagon and US intelligence agencies - led by the Central Intelligence Agency and the National Security Agency - were beginning to review what steps to take if the President determined that Iran was getting too close to producing a bomb.

A decade ago, the Obama administration conducted a highly classified cyber attack, code-named Olympic Games, at Iran's Natanz enrichment site. The breach neutralised centrifuges, which spin at supersonic speeds to enrich uranium, and destroyed about 1,000 of the 5,000 machines in operation.

If the US targets Iran's uranium enrichment operations, experts say, it is likely to take aim again at the Natanz site. But this time, the Iranians appear far better prepared.

And some US administration officials warn that acting now would be premature. Even if Iran possesses 800kg or 900kg of uranium, it would be insufficient for a single bomb.

That threshold is not likely to be crossed until later this summer.

NYTIMES, REUTERS