Serving and retired US officials warned that President Obama would be prepared to use military force to prevent Iran from acquiring a nuclear weapon if sanctions and diplomacy failed. - File Photo

WASHINGTON: Serving and retired US officials warned on Tuesday that President Barack Obama would be prepared to use military force to prevent Iran from acquiring a nuclear weapon if sanctions and diplomacy failed.

Tensions between Iran and the US reached a new high on Monday when Tehran announced that it had sentenced an Iranian-American man, Amir Hekmati, to death for allegedly spying for CIA.

On Tuesday, US officials told the media that Iran had confirmed the death sentence to America’s Swiss representatives in Tehran.

The Obama administration says the charges against Mr Hekmati, a 28-year-old former military translator, are a complete fabrication and wants him released.

Dennis Ross, who served two years on the US National Security Council and a year as Secretary of State Hillary Clinton`s special adviser on Iran, said he believed President Obama would use force to prevent Iran from going nuclear.

Earlier, America’s defence secretary and military chief also warned that developing a nuclear weapon would cross a red line, precipitating a US strike.

“They need to know that if they take that step, they’re going to get stopped”, Defence Secretary Leon Panetta told CBS News’ ‘Face the Nation’.

On the same program, Gen Martin Dempsey, chairman of the US Joint Chiefs of Staff, said he had been responsible for planning and positioning assets to be ready if ordered to take military action.

Asked whether the US military could take out Iran’s nuclear facilities, Gen Dempsey said: “I certainly want them to believe that’s the case.”

The US military chief said it was his responsibility to encourage the right degree of planning to understand the risks associated with any kind of military option.

In an interview to the Bloomberg media group, Mr Ross said that President Obama had ‘made it very clear’ that he regarded a nuclear-armed Iran as so great a threat to international security that `the Iranians should never think that there’s a reluctance to use the force` to stop them.

“There are consequences if you act militarily, and there’s big consequences if you don’t act,” said Mr Ross, who in a two hour interview at the Bloomberg Washington office laid out a detailed argument against those who say President Obama would sooner ‘contain’ a nuclear armed Iran than strike militarily.