In his private meetings on Sunday, Mitt Romney was hearing Israel’s assessment of Iran’s steady progress toward the bomb, and doubtless elaborating upon his previously declared commitment “to use any means possible to prevent Iran from going nuclear.”

Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak may well be inclined to take the Republican presidential candidate at his word. Romney has repeatedly slammed President Barack Obama for mishandling the Iranian threat, and went so far as to assert, in a Washington Post op-ed in March, that with Obama in the White House, Iran was on course to acquiring nuclear weapons.

The problem for Israel’s leadership duo is that Romney doesn’t run America. At least not yet. And by the time he does, if he does, Iran may have entered what Barak terms the “zone of immunity” — the advanced stage of its nuclear drive in which Israeli military intervention may not be capable of halting its progress.

Which is why this week’s most significant American visitor may not be the man who would be president but the man who is defense secretary, Leon Panetta, due here hard on Romney’s heels. Panetta will be meeting Barak this week for the ninth time in a year, according to one count — an extraordinary statistic that underlines both the unprecedented coordination between the two security establishments, and the acute American concern that Netanyahu and Barak will consider a resort to force in the very near future if they are not convinced of this US administration’s readiness to intervene militarily before it’s too late.

The Obama-Panetta rhetoric on Iran has featured phraseology similar to Romney’s. Obama told the pro-Israel lobby AIPAC in March that he “would use all elements of American power to pressure Iran and prevent it from acquiring a nuclear weapon.” Panetta, at the same conference, said that “military action is the last alternative when all else fails… But make no mistake, we will act if we have to.”

But can the Israel of purportedly trigger-happy Netanyahu and Barak, and the America of ostensibly diplomacy-obsessed Obama and Panetta, agree on when it is that “all else” will be deemed to have failed, and when military action can no longer be avoided?

US National Security Adviser Tom Donilon’s visit here two weeks ago was plainly another part of the Administration’s ongoing effort to convince the Israeli leadership that it is genuinely ready, capable and willing to resort to force if necessary — whether or not Donilon went into the specifics of a potential US strike, as Haaretz reported Sunday and the PMO denied.

Quietly, behind-the-scenes, too, the US is being careful to keep Israel fully in the loop regarding the progress — or lack thereof — on the diplomatic front, with Wendy Sherman, the US representative to the P5+1 talks, constantly updating and consulting with Israeli officials including National Security Adviser Yaakov Amidror.

Yet the different emphases between Washington and Jerusalem are out there for all to hear. The president and his senior officials publicly reiterate their belief that time has not run out on diplomacy, and that sanctions are having an ever-greater impact. The prime minister and his key ministers declare repeatedly that diplomacy just gives Iran “a freebie” to expand its stocks of enriched uranium and work on its delivery systems, that sanctions are not sufficiently crippling and that, as Barak restated only last Thursday, dealing with a would-be nuclear Iran today will be a lot less complex and costly than tackling a nuclear Iran tomorrow.

American officials are prone to say that Israel’s heated rhetoric has been extremely effective in alerting the international community to the gravity of the threat posed by Iran. By signaling that it may be poised to strike, they say, Israel has alarmed much of the international community into imposing greater economic pressure, more quickly, on Iran.

But to listen to the likes of Meir Dagan, the veteran former Mossad chief, or to Shaul Mofaz, who until less than two weeks ago was Netanyahu’s deputy, is to conclude that while the rhetoric may be heated, it is not empty. Dagan has been warning for the past year against an unwarranted Israeli readiness to use force against Iran. Mofaz, since leading Kadima back out of the coalition after a mere 70 days at the prime minister’s side, has dropped a series of heavy hints about Netanyahu’s ostensible inclination to “set out on operational adventures that will endanger the future of our young women and young men and the future of the citizens of Israel in the State of Israel.”

Netanyahu told AIPAC in March, that “I will never let my people live under the shadow of annihilation.” Romney would have him believe that he won’t have to. Obama says much the same thing.

But for all the frequent flying of Administration officials, intelligence heads and military chiefs, Netanyahu and Barak may simply not have complete faith in Obama. After all, the president does keep stressing the commitment to diplomacy and economic pressure. And Panetta has publicly made far more compelling a case for holding fire than for unleashing it.

Several months ago, the defense secretary set out an impassioned, comprehensive argument against a military strike by Israel, or the US, for that matter — and he did so in the unscripted, question-and-answer phase of a lecture, speaking spontaneously and thus, presumably, from the heart rather than the script.

Such an attack would “at best” delay Iran’s nuclear program by “one, possibly two years… Frankly, some of those targets are very difficult to get at,” he told the Brookings Institution in December. A strike would “ultimately not destroy their ability to produce an atomic weapon,” he said, and would have “unintended consequences… A regime that is isolated would suddenly be able to reestablish itself, suddenly be able to get support in the region….”

The US, Panetta went on, warming to his theme, “would obviously be blamed and we could possibly be the target of retaliation from Iran, striking our ships, striking our military bases.”

Then there were the “severe economic consequences,” he said, “that could impact a very fragile economy in Europe and a fragile economy here in the United States.”

And finally, military intervention could cause “an escalation” that would “not only involve many lives, but I think could consume the Middle East in a confrontation and a conflict that we would regret.”

Granted, Panetta added a few moments later, “You always have… the last resort of military action, but it must be the last resort, not the first.”

After that presentation, it’s unlikely the Iranians would be bracing for American military action. And those remarks must have been pored over, too, in Jerusalem.

It is hard to imagine a president Romney, or his defense secretary, speaking in similar vein — though nothing is impossible, of course. But for Netanyahu and Barak, a Romney presidency, if it comes at all, might come too late.