TWO MONTHS ago we questioned a decision by Defense Secretary Leon Panetta to spell out publicly his objections to an Israeli military strike against Iran’s nuclear program — a speech that must have cheered the commanders of the Iranian Revolutionary Guard. Now Mr. Panetta has indirectly caused a similar stir: After a conversation with Mr. Panetta this month, The Post’s David Ignatius reported that the Pentagon chief “believes there is a strong likelihood that Israel will strike Iran in April, May or June.”

What could explain this public undercutting of one of America’s closest allies? The unfortunate answer seems to be a lack of strategic agreement or basic trust between the Obama administration and the Israeli government of Benjamin Netanyahu. A senior U.S. intelligence official recently said that Israel has grown reticent about discussing a possible attack on Iran and had declined to offer an assurance that it would consult Washington before acting. That leaves the administration facing the possibility that it will be presented with an Israeli-Iranian conflict that could expand to encompass U.S. forces and allies in the Persian Gulf and trigger unforeseeable consequences in the larger Middle East.

We continue to believe that military action against Iran, by Israel or the United States, is not yet necessary or wise. U.S. and Israeli officials share an assessment that, though Iran is building up nuclear capability, it has not taken decisive steps toward building a bomb. In the meantime, the pressures on its leadership — from sanctions, sabotage, the disarray of allies such as Syria and domestic discontent — are growing. The best strategy for now is to fan those flames, which could cause the regime to retreat or even to fall. On that, we agree with the Obama administration.

Israel has two reasons for judging the matter differently. While the Obama administration suggests that only a clear Iranian attempt to produce a nuclear weapon would justify military intervention, Israel believes that Iran’s acquisition of the capacity to do so — achieving the status of a threshold nuclear power, like India and Pakistan before 1997 — would also be intolerable. That’s understandable for a country within missile range of a regime that has called for the extinction of the Jewish state.

Another factor is more subject to U.S. influence. Israeli commanders judge that in a few months, once Iran has fully prepared a new nuclear facility located under a mountain, Israel’s capacity to disable the program with air strikes will be greatly reduced. The United States would retain a military window of opportunity for longer. But can the Netanyahu government count on the Obama administration to act if a moment of truth arrives?

For now, several top Israeli officials are skeptical. That is where Mr. Panetta and Mr. Obama should be making an effort. Rather than publicly arguing with Israel, they should be more clearly spelling out U.S. willingness to take military action if Iran is discovered taking steps toward bomb-making, such as enriching its uranium beyond present levels or expelling U.N. inspectors. Saying “all options are on the table” is not enough; the Obama administration should be explicit about Iranian actions that will violate its red lines — and what the consequences will be.