JERUSALEM — In the wake of the killing Friday of Iran's top nuclear scientist , the questions have quickly shifted from who carried out the brazen daylight attack to why.

Commentators, brushing past Israel’s refusal to comment on an assassination that showed the hallmarks of an Israeli clandestine operation, have moved on to asking what Israeli Prime Minister Benjamin Netanyahu hoped to achieve.

Did he seek to draw Tehran into a military response that would, in turn, justify an American assault on Iran’s nuclear program in the waning weeks of the Trump administration?

To spoil conditions for the diplomatic reset that President-elect Joe Biden is expected to seek with Iran?

Or did Netanyahu simply seize an opportunity to take out Moh­sen Fakhrizadeh, the brains of Iran’s nuclear program who topped Israel’s target list, in hopes that Iran would show restraint in its response, as it has since the attack?

Each theory — or combination of them — has its proponents among Israel’s national security veterans and analysts, a community used to interpreting the motives of a leader known to be both inherently cautious and devoted to the glow of a bold stroke.

The task of teasing out the strategy is complicated by the current complex brew of circumstances, which include the shifting alliances of the Middle East, Netanyahu’s own legal and political troubles and, most critical, the winding down of the Trump era.

Netanyahu is wary of Biden’s promise to offer Iran “a diplomatic path” back to compliance, and by some accounts, he is pushing President Trump to strike a decisive blow against Iran’s nuclear program as a parting shot.

“For a month and a half, Bibi’s leverage vis-a-vis the Iranians will be: ‘If you respond, all hell can break loose,’ ” said Yoel Guzansky, the former head of the Iran desk of Israel’s National ­Security Council, using Netanyahu’s nickname. “This guy in Washington, you don’t know what he will do before leaving office.”

The prime minister, who has seen his popularity plummet as the coronavirus pandemic wreaks havoc on Israel’s economy and who is battling charges of bribery and fraud in a Jerusalem court, knows that taking the fight to the country’s No. 1 enemy could rally vital popular support at home.

“Generally, it is true that Bibi has been cautious when it comes to military action,” said Chuck Freilich, a former Israeli deputy national security adviser. “But in this case he is facing a combination of not just strategic goals but political ones. He needs dramatic developments to show that he is Israel’s irreplaceable leader.”

Freilich said some national security experts believe that Netanyahu is ready to spark a full-scale U.S. deployment of bunker busters against Iran’s nuclear centrifuges before Biden takes control of the Pentagon on Jan. 20.

“Israel is ready to press for the resolution of the Iranian nuclear issue,” Freilich said. “It’s been with us for 30 years and it’s time to put it to rest.”

That strategy may have been advisable six months ago, Freilich said. But now it risks spoiling Israel’s relationship with an incoming president who has previously been friendly to Israeli interests.

But others conclude that Netanyahu took the risk of hitting Fakhrizadeh, whom the prime minister had singled out as enemy No. 1 in a 2018 news conference, in hopes that Iran would show restraint.

The sophistication of the assassination, which has been attributed variously to a squad of hit men, a car bomb or a satellite-controlled superweapon, was of the type that takes months of planning. If an opportunity arose to pull the trigger, Netanyahu may have given the okay despite the tensions of the moment, not in an effort to ramp them up.

“Bibi doesn’t want a war with Iran,” said Yossi Melman, who has written extensively about Israel’s clandestine operations. “He’s taking a calculated risk that the Iranians will promise revenge but they will not dare send missiles.”

Hard-liners in Iran are pressing leaders to respond forcefully to the humiliation of the daylight attack on home soil. The hawkish Kayhan newspaper on Sunday called on Iran to strike Haifa, a port city near Israel’s northern border with Lebanon, and inflict “heavy human casualties,” if Israel’s role in the assassination could be proved.

But the regime and its supreme leader, Ayatollah Ali Khamenei, facing crippling economic sanctions, a heavy death toll from the coronavirus crisis, and growing domestic unrest, will tread with caution, said Meir Javedanfar, an Iranian-born lecturer on Iranian affairs at IDC Herzliya.

“Khamenei can play the tough guy with the people of Iran, but with the international community, he needs to be more careful,” he said.

The Iranians’ lack of action since Friday suggests they may hold their fire as they wait to see what a new White House will bring. “If they don’t do something in the next few days, they are probably not going to do it before Biden comes,” Freilich said.

Israel is bracing for a counterattack in any case. Its embassies are on alert. The Israeli Defense Ministry is coordinating with the United Arab Emirates in the expectation that thousands of Israeli tourists about to descend on Dubai and Abu Dhabi — following the signing of the ­Israeli-UAE peace accord — are potential targets for an Iranian attack, according to Israel’s Channel 12 News.

Whatever motives drove Friday’s attack, it has presented the State Department of the incoming Biden administration with a roiled diplomatic environment. The emerging alliance between Israel and its gulf Arab neighbors — which so far formally include the UAE and Bahrain with signs of a similar thaw in Saudi Arabia — presents both Iran and Biden with a more unified regional bloc.

The killing of Fakhrizadeh came shortly after a series of meetings — some announced, others rumored — involving top-ranking American, Israeli and Saudi officials. Two days after U.S. Secretary of State Mike Pompeo met with Netanyahu in Israel, Netanyahu reportedly flew secretly on a private plane to Saudi Arabia to meet with Pompeo and Crown Prince Mohammed bin Salman. The Saudis have denied that Netanyahu was present.

“If Pompeo and bin Salman and Bibi are sitting together a week ago, and Trump is leaving the White House in another month, and Bibi is maybe getting ready for elections, the context of what happened on Friday is a different context,” Guzansky said.

The word to Tehran is that a wall of foes is ready to confront it. The word to Biden is that its allies in the region are shoulder-to-shoulder in viewing Iran as their primary threat and they want their views front and center in Washington.

“The message, even if unintended, is that Israel will play hardball on the Iranian issue, rather than cooperating in developing a joint response,” Freilich said.