A Syrian military source and the Russian Defense Ministry said Israeli F-15 fighter jets carried out Monday’s strike from Lebanese airspace. (Amir Cohen/Reuters)

The prospect of a U.S. strike on Syria in retaliation for an alleged chemical attack, coupled with a missile raid apparently carried out by Israel that killed Iranian military personnel, has underscored the risk that the conflict is on the brink of a dangerous escalation.

Syria and Russia accused Israel of carrying out the strike against a Syrian base where Iranians were stationed. More than ever, Syria is in danger of becoming an arena for the settling of scores among world powers.

On Tuesday, Iran’s Tasnim news agency said seven Iranian were killed in the airstrike that left a total of at least 14 people dead. The Tasnim report — which could not be independently verified — raised the Iranian death toll at the base, which also houses Russians and members of the Lebanese Hezbollah militia.

Earlier, Iran’s Fars news agency said four Iranians were among the dead.

Despite President Trump’s warning that Syrian President Bashar al-Assad would pay a “big price” for his military’s alleged use of poison, analysts questioned whether U.S. strikes would influence the course of events on the battlefield and stem the seeming inevitability of a Syrian government victory over its opponents.

On Monday, Syrian rebels began evacuating the Damascus suburb where the alleged poison gas attack took place, after agreeing to a surrender deal that will restore government control over the area for the first time in six years.

U.S. strikes are not going to alter the Assad government’s trajectory, “and they may make things worse,” said Emile Hokayem of the International Institute for Strategic Studies. “There might be a narrow, self-satisfying strike, but as long as there is no bigger perspective or broader strategy for the whole conflict, it may just fuel escalation without meeting any objective.”

He added, “The time for intervention has passed.”

Syria was already on edge, braced for military retaliation from the United States, when missiles struck an air base near Palmyra in the east of the province of Homs in the pre-dawn hours Monday, prompting accusations from the Syrian government that U.S. forces were responsible. After the Pentagon issued a strong denial, Russia and Syria then said it was Israel that had attacked the T-4 base.

According to Russia’s Defense Ministry, Israel carried out the attack by launching eight guided missiles from two F-15 planes, and Syria shot down five of the missiles.

Israel did not acknowledge carrying out the strike.

In Washington, Trump said his team was still debating how to punish Damascus for the alleged use of chemical weapons in the attack Saturday on the town of Douma, the last major rebel-held urban stronghold in the suburb of Eastern Ghouta.

Videos, denials

Videos of the incident posted online showed piles of crumpled bodies, many of them women and children, crammed together in an apartment building, wide-eyed and with foam on their mouths, suggesting that a poisonous gas had killed them. The Syrian American Medical Society said it had counted 49 people killed in the attack, and the toll could rise as more bodies are identified.

Russia and Syria deny that chemical weapons were used.

The main rebel group in the area, Jaish al-Islam, had been holding out for a settlement that would allow it to remain and join a peace process proposed by the Russians under which rebel-held territories would eventually reconcile with the Assad government.

After the alleged chemical attack, the rebels relented, agreeing to evacuate to rebel-held areas in the north and allow the government to retake control of the enclave, residents said. The attack came as the final straw following weeks of sustained airstrikes that killed hundreds of people and injured thousands. The bombardment had kept more than 100,000 people huddled in basements and shelters, said a medical student in Douma who has worked with the opposition and spoke on the condition of anonymity for safety reasons.

“When you know there is no one to support you and when you know that the whole world is going to be silent no matter how many times you have been targeted, your choice will be to say: ‘Okay, stop the killings and I will do whatever you like,’ ” the student said. “People can no longer handle it.”

On Monday, the rebels began boarding buses for northern Syria alongside several thousand civilians who fear being detained for their opposition activities once government control returns.

The departure was broadcast by state television and trumpeted as yet another major military victory for Assad over his opponents. Eastern Ghouta was the last significant area controlled by the rebels in the vicinity of the capital, and though a government victory was a foregone conclusion after troops launched a major offensive in February, the capitulation came as yet another milestone in the Assad government’s march toward defeating its opponents.

Limited clout

At the same time, Trump’s declaration last week that he wants to pull U.S. troops out of northeastern Syria further undermines the impact that strikes might have on slowing the government’s progress, said Faysal Itani of the Atlantic Council in Washington.

“A president who says he wants to get the hell out of Syria is not really in a position to threaten the military progress of the regime,” he said. “If Assad has boxed us into a position where we’ve got to throw some missiles at him, it doesn’t really change the picture.”

A small attack such as the one a year ago conducted in retaliation for a sarin gas attack that killed civilians in the northern Syrian town of Khan Sheikhoun wouldn’t make a difference, he said. A larger one would run the risk of confrontation with Iran and Russia, which have both repeatedly expressed their desire to see the United States leave Syria.

The small U.S. force of about 2,000 troops deployed in northeastern Syria alongside Syria’s Kurds is particularly vulnerable to revenge attacks from Iran and Syria, Itani said. Iran also could push back against the United States in places such as Iraq, where U.S. troops are present.

Russia has warned that U.S. strikes in Syria would have “grave consequences,” according to a Foreign Ministry statement on Sunday. Given the heightened tensions between Russia and the United States on other issues, Russian President Vladimir Putin may seize on U.S. strikes as an opportunity to leverage a confrontation and force the United States to the negotiating table, said Russian analyst Vladimir Frolov.

“The Cuban missile crisis might be the template Putin is looking at right now,” he said. “Force a military showdown, then call Trump to a summit to decrease tensions.

“Russia wants the U.S. out of Syria as soon as possible, so if we have a clash and Trump retreats, Putin scores twice,” he added.

Israeli concerns

Israel, meanwhile, which has repeatedly expressed concerns about the expanding Iranian military presence in Syria as the Syrian government consolidates its control, may have seen Trump’s threats on Sunday as an opportunity, said Michael Horowitz, a senior analyst at Le Beck International, a Middle East-based geopolitical and security consultancy.

“The timing of the strike isn’t coincidental,” he said. “By striking [Assad] and his Iranian allies just a day after Trump warned them of the price they would pay . . . Israel mitigates the risk of an Iranian response,” he said. “Israel has been trying to convince Washington to adopt a more pro-active, anti-Iran strategy in Syria, and certainly sees Trump’s rhetoric in the wake of the chemical attack as an opportunity.”

Russia and Syria have consistently denied all allegations of chemical attacks during the ­seven-year-long Syrian war, and in this instance they have accused the rebels of staging a “false flag” incident Saturday to trigger U.S. intervention. As Russian troops moved into the area Monday in the wake of the evacuating fighters, Syrian doctors visited the site of the alleged chemical attack and found no evidence that poisonous gases had been used, Russia’s Defense Ministry said in a statement.

The Eastern Ghouta area has been under rebel control for the past six years and completely surrounded by the government for nearly five years, making it impossible to independently verify the accounts of a chemical attack.

The suburb, a cluster of mostly rural towns and villages that was one of the centers of the 2011 uprising against Assad, was also the site of a 2013 sarin gas attack that killed as many as 1,400 people.

Cunningham reported from Istanbul. Ruth Eglash in Jerusalem and Suzan Haidamous and Asma Ajroudi in Beirut contributed to this report.