Would US back Israeli attack on Iran?

US President Barack Obama has stepped up pressure on Iran over its nuclear ambitions by signing an executive order to implement sanctions passed by Congress late last year.

Amid speculation that Israel could be preparing a pre-emptive strike against Iranian nuclear facilities, some have wondered whether Washington would also support military action by its ally.

But Leon Panetta, the US defense secretary, has said that attacking Iran would be "a conflict that we would regret", only serving to delay Iran's abilities to develop nuclear weapons, making the US a target for Iranian retribution and having dire economic consequences for the US and Europe.

Al Jazeera's Patty Culhane reports from Washington.