As for timing, the US will not give Israel the green light to attack Iran until another carrier task for joins the two already in the Gulf (USS Enterprise and USS Stennis). The Pentagon has indicated they are prepared to send the USS Nimitz to the Gulf to arrive in April. This indicates that the most likely timing of the attack will be between April and July of this year. The transfer of the Nimitz is being contested by CENTCOM commander Admiral Fallon. He may even be replaced for making statements inferring that an attack on Iran will not occur on his watch.