Question is whether the US is now using its forces throughout the region, plus those currently in Israel to make it clear to Israel that any attack on Iran by Israel will not be tolerated.
Israel's propensity to act without thinking of wider consequences, is well known, reasons are understandabke. So maybe Obama is accepting Iranian nukes as a fait accompli to be dealt with in time but needs to keep Israel in check from starting WW3.
As Iranian President has 18 months left to serve on his term of office and can not stand again then maybe allowing time to take its natural course may be a considered option...........as unlikely as that seems.
US will know that having a single Carrier group in same area requires lots of resupply, having 3 will use up lots of resources very quickly if they are there for an indefinite time which is why I see US carriers moving within 2 weeks.