Iran has retaliated directly against Israel for the killings of its senior generals in Damascus, Syria, with an onslaught of more than 300 drones and missiles aimed at restoring its credibility and deterrence, officials and analysts say.

That represents a moment of great risk, with key questions still to answer, they say. Has Iran’s attack been enough to satisfy its calls for revenge? Or given the relatively paltry results — almost all of the drones and missiles were intercepted by Israel and the United States — will it feel obligated to strike again? And will Benjamin Netanyahu, the prime minister of Israel, see the strong performance by his country’s air defenses as a sufficient response? Or will he choose to escalate further with an attack on Iran itself?

Now that Iran has attacked Israel as it promised to do, it will want to avoid a broader war, the officials and analysts say, noting that the Iranians targeted only military sites in an apparent effort to avoid civilian casualties and advertised their attack well in advance.

“Iran’s government appears to have concluded that the Damascus strike was a strategic inflection point, where failure to retaliate would carry more downsides than benefits,” said Ali Vaez, the Iran director of the International Crisis Group. “But in doing so, the shadow war it has been waging with Israel for years now threatens to turn into a very real and very damaging conflict,” one that could drag in the United States, he said.

“The Iranians have for now played their card,” said Sanam Vakil, director of the Middle East and North Africa program at Chatham House. “They made a choice to call Israel’s bluff, and they felt they needed to do so, because they see the last six months as a persistent effort to set them back across the region.”

On Sunday, Iranian leaders said the military operation against Israel was over, but warned that they could launch a bigger one depending on Israel’s response.

Brig. Gen. Mohammad Bagheri, Iran’s top military officer, said the “operation yielded its complete result” and “there is no intention to continue it.” But, he added, if Israel attacked Iran on its own soil, or elsewhere, “our next operation will be much bigger than this.”

For years, Iran took blow after blow from Israel: assassinations of its nuclear scientists and military commanders, explosions at its nuclear and military bases, cyberattacks, intelligence infiltrations, an embarrassing theft of nuclear documents and recent attacks on its critical infrastructure.

But since the Hamas-led assault of Oct. 7 prompted Israel to go to war in Gaza, Israel has intensified its attacks on Iranian interests and commanders in Syria. In a series of strikes from December onward, Israel has assassinated at least 18 Iranian commanders and military personnel from the Quds Force, the elite unit of the Islamic Revolutionary Guards Corps that operates outside Iran’s borders, Iranian media said.

Iran’s government has been criticized by hard-liner supporters for its cautious posture during the war in Gaza.

With the attacks this weekend, Ms. Vakil said: “I think Tehran saw a need to draw this red line and make it clear to Israel that Iran does have red lines and would not continue to tolerate the slow degradation of its position.”

Tehran felt it had to respond, even if its attack prompted firm American backing and widespread Western diplomatic support for Israel, taking some of the heat off Israel over its war in Gaza, at least temporarily, and again isolated Iran.

Now, Ms. Vakil said, the two sides were in a standoff in which both were prepared for escalation despite knowing it would cause huge damage to themselves.

At the same time, the old equation has changed, with Israel and Iran hitting each other directly, on each other’s territory, and not through Iranian proxies abroad.

The Israeli strike on Iran’s Embassy compound in Damascus, followed by a direct Iranian strike on Israel, represents a dangerous new chapter in the long, sometimes hidden war between Israel and Iran, which has said it wants Israel to be wiped off the map. Sometimes known as “the shadow war,” the conflict has been carried out mainly between Israel and Iran’s allies and proxies — in Gaza, southern Lebanon, Iraq, Yemen and Syria.

Both sides claim they are acting in national self-defense — Israel against groups committed to its destruction, with Iran as their prime ally and controller, and Iran against any potential Israeli war against it, often in the name of the Palestinians.

Iran increasingly refers to its rapidly expanding nuclear program, which has enriched uranium to near weapons-grade, as a deterrent against Israel, while at the same time denying that it has any intention of building a nuclear weapon. But increasingly Iran is considered by experts as a nuclear-threshold state, able to create weapons-grade nuclear material within weeks and a crude nuclear weapon within a year or so.

Iran is also going through a slow and complicated transition as Ayatollah Ali Khamenei, the supreme leader and commander in chief, is said to be ailing and faced a 2022 domestic uprising, led by women, that demanded an end to clerical rule.

Mr. Khamenei himself ordered the strikes on Israel from inside Iran to send a clear message that Iran was shifting from “strategic patience” to a more active deterrence, according to four Iranian officials, two of them members of the Revolutionary Guards. They requested anonymity because they were not authorized to speak publicly.

“Iran’s operation has a crystal-clear message to Israel and its allies that the rules of the game have changed and from now on, if Israel strikes any Iranian targets or kills any Iranians, we are willing to strike in a big way and from our own soil,” Nasser Imani, a prominent analyst based in Tehran who is close to the government, said in a telephone interview. “The days of covert operations and patience are over.”

Iran also wanted to seize what it viewed as a “golden opportunity” to retaliate at this scale, because Israel was being so widely criticized over Gaza, including by its key allies, like the United States, Mr. Imani said.

Iran’s reach for regional hegemony, enhanced by its proxies and its nuclear abilities, has antagonized the traditional Sunni Arab governments of the region, including Egypt, Saudi Arabia, Jordan and Gulf nations. The Islamic Revolution that overthrew the monarchy in 1979 was at its start aimed at regional revolution, overthrowing these governments, most of which are monarchies or military dictatorships, so Israel’s efforts to limit the power of Iran, a non-Arab Shiite nation, have had quiet support from Arab countries, including Israel’s war against Hamas.

Now the risks of regional escalation have gone up considerably. Iran has been careful during the war in Gaza to restrain its proxies surrounding Israel against major strikes, and to avoid major Israeli retaliation against Hezbollah in southern Lebanon in particular. Hezbollah, with its many thousands of rockets aimed at Israel, is considered a major deterrent preventing Israel from directly attacking Iran and especially its nuclear and missile program.

Given Iran’s new isolation after this attack, Israel should not respond, said Bruno Tertrais, the deputy director of the Foundation for Strategic Research in France. “But a threshold has been crossed,” he said. And the threshold for “a massive Israeli attack on Iranian territory,” he continued, “always an extreme option for Israel whatever the commentators say — is now lowered.”

Mr. Netanyahu, who has been warning of the threat from Iran for two decades and faces severe pressure to respond from within his shaky far-right coalition, may choose to riposte with more force, either at Iran directly or at Hezbollah. But Washington, not having been warned of the Damascus attack, is likely to insist on prior consultation now.

But the modest outcome of the Iranian attacks “may strengthen an Israeli perception that Tehran is on the back foot, lacking the willpower and capacity for deeper engagement, and that now is the moment for Israel to inflict a long sought after deeper blow on Iran and its regional proxies,” said Julien Barnes-Dacey, the director of Middle East and North Africa for the European Council on Foreign Relations.

Israel’s challenge was always “to thwart the main thrust of the attack while still leaving an opening that will enable the Iranians to say that they achieved their goal,” wrote Nahum Barnea, a commentator for Yedioth Ahronoth, an Israeli daily. The danger is from the two extremes, he continued: “An overly successful Iranian operation is liable to devolve into a regional war; an overly failed Iranian operation will invite another Iranian operation.”

Iran’s mission to the United Nations suggested in a statement on social media on Saturday that if Israel does not respond, Iran would stand down.

“The matter can be deemed concluded. However, should the Israeli regime make another mistake, Iran’s response will be considerably more severe,” the statement said. It also warned that “the U.S. MUST STAY AWAY!”

Leily Nikounazar contributed reporting.