– 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.

Despite President Donald Trump's warning that Syrian President Bashar 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 predawn hours, 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.

Iran's Fars News Agency said four Iranians were among at least 14 people reportedly killed at the base, which also houses Russians and members of the Lebanese Hezbollah militia. 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 whether to punish Damascus for the alleged use of chemical weapons in the Saturday attack on the town of Douma, the last major rebel-held urban stronghold in the suburb of Eastern Ghouta.

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 a poisonous gas had killed them. The Syrian American Medical Society said it had counted 49 people killed in the attack, and the toll may 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.

"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: 'OK, 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.

The departure was broadcast by state TV and trumpeted as yet another major military victory for Assad over his opponents.