"[T]here has to be real trust, and so far I don’t think it’s there"

Some argue, therefore, that if Mr. Netanyahu decides to attack Iran’s nuclear facilities, he is more likely to do so before the November election, figuring Mr. Obama would find his hand forced into at least tacitly supporting the move.

But others make two counterarguments. The first is that Mr. Netanyahu believes that Mr. Obama is likely to be re-elected and does not want to alienate him. The second is that no matter who is in the Oval Office, Israel will not outsource what it views as its vital security interests based on an American promise to take military action if sanctions fail. Israel’s goal is an American attack on Iran, but it seems unlikely to wait till it no longer can do it by itself…

All of this is making for complex calculations on both sides. If Mr. Obama trusted Mr. Netanyahu more, he might issue a more muscular statement of military threat to Iran, confident that Israel would not move too quickly without coordination. And if Mr. Netanyahu trusted Mr. Obama more, he would be less jumpy over every statement of caution emerging from Washington, like one by Gen. Martin E. Dempsey, chairman of the Joint Chiefs of Staff, that it would not be prudent to decide to attack Iran now because it would destabilize the region.