United States intelligence officials assert that Iran has the means to build a nuclear weapon but has not yet decided to follow through, in contrast to Israel's insistence that time is running out to stop Iran from developing such a weapon.
But Iran was likely to strike out at US interests if it felt threatened, Director of National Intelligence James Clapper told the Senate Intelligence Committee in an annual report to Congress on threats facing America.
Citing last year's thwarted Iranian plot to kill the Saudi ambassador in the US, "some Iranian officials probably including Supreme Leader Ali Khamenei ... are now more willing to conduct an attack in the US in response to real or perceived US actions that threaten the regime", Clapper said.
Iran had the technical ability to build a nuclear weapon, Clapper said. But he, CIA Director David Petraeus and others reasserted their stance that Iran was not building nuclear weapons.
"There is dissension and debate in the political hierarchy of Iran" over whether to build a weapon, Clapper said.
"There is not unanimity about this" as Iranian political officials weigh the regional prestige they believe they may gain by possessing a weapon against the cost of further international sanctions and the risk of retaliatory military action by Israel or the West.
Petraeus said the latest round of sanctions against the regime was beginning to bite, with a run on Iranian banks in recent weeks, but he conceded that the "clock is ticking" as Iran moved ahead enriching uranium to a grade that was below weapons-ready, but higher than normal for regular industrial use.
Defence Secretary Leon Panetta said this week that the Iranians could build a bomb quickly.
"If they decided to do it, it would probably take them about a year to be able to produce a bomb and then possibly another one to two years in order to put it on a deliverable vehicle of some sort in order to deliver that weapon," Panetta said.
Israeli Defence Minister Ehud Barak said last week that Iran was proceeding towards nuclear weapons capability and time was "urgently running out".
Israel has set up a specialist commando unit designed to carry out missions deep inside enemy territory amid growing consensus in government circles that military strikes must be contemplated if economic sanctions do not halt Iran's nuclear programme.
The Tehran regime has repeatedly claimed that Israeli, US and British agents are responsible for the assassination of six scientists involved in the country's nuclear programme - a charge rejected by London and Washington.
- Independent, AP