Having served as C.I.A. director and secretary of defense during a meltdown in relations between an American president and an Israeli prime minister, Leon Panetta says there is now danger in the other extreme. “If it looks like the United States is going to do whatever Israel’s bidding is, on any issue, then I think the United States loses any leverage,” he said. “Our fundamental goal has to be to protect our national security interests. What is in the United States’ interest? And yes, we are a friend and an ally of Israel, but I think we always have to maintain a relationship that looks at the bigger picture of that region and what needs to be done to preserve peace in that region.” In recent days, Trump has used support for Israel as a kind of litmus test for American Jews, saying that Jews who opposed him were being “disloyal” both to Israel and the Jewish people.

And yet Trump’s last-minute decision to abort the attack in June led to a concern among Iran hawks in both Israel and the United States: that the president ultimately might not have the resolve to confront the threat with military force. The hawks also had reason to fear that two other partners in the anti-Iran coalition — Saudi Arabia and the U.A.E. — might read any “softening” of Trump’s position on Iran as a sign that they, too, must adjust their positions out of fear of being left alone to deal with their regional nemesis. Both countries once aggressively lobbied the Trump administration to take a hard-line position on Iran and advocated the United States’ leaving the J.C.P.O.A. But the U.A.E. recently announced a drawdown of its military involvement in Yemen — where Emirati and Saudi troops have been battling a rebel group that receives military support from Iran — and sent a delegation to Tehran to discuss maritime security.

Once again, more than a decade after they first raised the subject with American officials, Israeli officials have been considering the possibility of a unilateral strike against Iran. Unlike with Bush and Obama, there is greater confidence that Trump wouldn’t stand in the way. Netanyahu has recently been flexing Israeli muscle around the Middle East — launching hundreds of raids into Syria against Iranian and Hezbollah arms stores and troop concentrations, and undertaking an even bolder operation in July against a base in eastern Iraq that, Israeli intelligence believed, was being used to store long-range guided missiles en route to Iranian forces in Syria.

The threat of war could be a bluff, or an election ploy. But it also represents a dangerous confluence of interests: an American president often reluctant to use military force and an Israeli prime minister looking to deal with unfinished business.