JERUSALEM, May 17: The US had plans in place to attack Iran if necessary to prevent it from developing nuclear weapons, Washington’s envoy to Israel said, days ahead of a crucial round of nuclear talks with Tehran.

Dan Shapiro's message resonated on Thursday far beyond the closed forum in which it was made: Iran should not test Washington’s resolve to act on its promise to strike if diplomacy and sanctions fail to pressure Tehran to abandon its nuclear programme.

Shapiro told the Israel Bar Association the US hoped it would not have to resort to military force. “But that doesn’t mean that option is not fully available. Not just available, but it's ready,” he said.

“The necessary planning has been done to ensure that it’s ready.”

Iran says its nuclear programme is for peaceful purposes, like energy production. The US and Israel claim Iran is pursuing nuclear weapons, but differences have emerged in how to persuade Tehran to curb its programme.

Washington says diplomacy and economic sanctions must be given chance to run their course, and is taking the lead in the ongoing talks between six global powers and Iran.

Israel, while saying it would prefer a diplomatic solution, has expressed scepticism about the talks and says time is running out for military action to be effective.

President Barack Obama has assured Israel that the US is prepared to take military action if necessary, and it is standard procedure for armies to draw up plans for a broad range of possible scenarios. But Shapiro’s comments were the most explicit sign yet that preparations have been stepped up.

In his speech, Shapiro acknowledged the clock is ticking. “We do believe there is time. Some time, not an unlimited amount of time,” he said. “But at a certain point, we may have to make a judgment that the diplomacy will not work.”—AP