Twenty months ago, in the aftermath of Hamas’s attack on Israel in October 2023, Benjamin Netanyahu’s political career teetered on a precipice. As Israel’s prime minister, he had overseen the deadliest military lapse in the country’s history, wrecking his security credentials and collapsing support for his government.

The United States’ overnight attack on Iran on Sunday, coupled with Israel’s own recent strikes, has taken Mr. Netanyahu to the brink of political redemption. For decades, he dreamed of thwarting Iran’s nuclear program, defining it as the greatest threat to Israel’s future, and its destruction as his highest military priority.

Now, he is as close to reaching that goal as he may ever get. To many Israelis, it is a success that helps to revive his reputation as a guardian of their security, raises his chances of re-election and, depending on how the next weeks develop, could cement his historical legacy.

“This night marks Netanyahu’s greatest achievement since he first came to power in 1996,” said Mazal Mualem, a biographer of Mr. Netanyahu. “From the perspective of the public, he has achieved a victory against what is considered the greatest threat to Israel since its founding.”

In Iran, the short-term consequences of the U.S. strikes have yet to play out. It is not yet clear if they completely destroyed their targets. Even if they did, Israel could continue to attack Iran, seeking to further destabilize the Iranian government.

Iran fired another barrage of missiles at Israel on Sunday, and many fear it will retaliate against U.S. military bases, embassies and interests. That could prompt more American and Israeli strikes on Iran, lengthening the war.

Alternatively, if the Iranian response is limited, the Israeli government may wind down the war, satisfied that it has achieved most of what it hoped for, and conscious that a longer conflict risks straining Israel’s air-defense system.

“The ball is in the Iranian yard,” said Maj. Gen. Amos Yadlin, a former head of Israeli military intelligence. “If Iran keeps on firing missiles, Israel will continue its own strikes and pursue more achievements, targeting Iran’s missile launchers and missile factories, its oil industry and its civilian leadership.”

Regardless of what happens next in Iran, Mr. Netanyahu’s success has already changed the political landscape in Israel. After Israel began striking Iran more than a week ago, broadcasters published opinion polling that suggested his coalition had greater support than at almost any point since the start of Israel’s war with Hamas in late 2023.

On Sunday morning, his biggest domestic critics even applauded the success of his campaign, including his achievement in persuading President Trump to join the battle and destroy targets that Israeli warplanes could not reach.

“I don’t have a problem with him enjoying this moment,” Yair Lapid, the leader of the opposition, said of Mr. Netanyahu on Sunday in a radio interview. “This is a success for Netanyahu, a success for Trump, and a success for the free world. This is what needed to happen.”

Buoyed by the blow against Iran, Mr. Netanyahu could show greater flexibility in the negotiations to reach a new truce and hostage release deal in Gaza, analysts said.

For most of the war, he has avoided reaching a deal in Gaza that would allow Hamas’s remnant leadership to retain significant influence in the territory. Mr. Netanyahu’s far-right coalition partners repeatedly threatened to quit the government if the Gaza war ended without Hamas’s total defeat. And with Mr. Netanyahu’s party languishing in the polls, he appeared unwilling to make concessions in the talks that risked the collapse of his political alliance, most recently during renewed negotiations in May.

Now, Mr. Netanyahu has options. Having exacted a price from Iran, Hamas’s biggest benefactor, Mr. Netanyahu may be able to persuade his coalition to compromise in the talks with Hamas itself, according to his former adviser, Nadav Shtrauchler.

“Soon he hopefully will be able to say: ‘We changed the Middle East. Now we need to be more flexible on other fronts — in Gaza and regarding the hostages,’” Mr. Shtrauchler said. “It will not happen tomorrow but a window of opportunity has been opened.”

If he does agree to a cease-fire in Gaza, that in turn would raise the chances of Mr. Netanyahu’s achieving another long-held ambition: the normalization of relations between Israel and Saudi Arabia, the Arab world’s most powerful country.

In talks last year with U.S. diplomats, officials said, Saudi Arabia signaled its openness to such a landmark deal — if the war ends in Gaza and if Mr. Netanyahu agrees to Palestinian sovereignty. The former is still a long shot, and the latter is even less likely, given Mr. Netanyahu’s resistance to a Palestinian state. But since he may be less beholden to his far-right allies, the prime minister could have more room for maneuver.

“It’s now easier for him to make big diplomatic moves like a Saudi deal,” Mr. Shtrauchler said. “If he has time today, he will be smoking a big cigar. Even if it’s not over yet, he has achieved one of his life missions, and is on the way to achieving others.”

Aaron Boxerman, Myra Noveck and Gabby Sobelman contributed reporting.