WASHINGTON — As Syria’s seven-year civil war enters a climactic phase, the Trump administration is grappling with how to address the emerging political dynamics. President Bashar al-Assad has retaken control of most of Syrian territory, and experts said there is almost no chance that rebel groups will topple him or change the course of the war.
But this week, Russia and Turkey proposed a demilitarized zone to stop a military offensive that Mr. Assad had planned against Idlib Province, the last major rebel enclave in Syria. Even a delay in the rampage would buy time for the United States to help draw up new strategies for dealing with Syria if it definitively falls under Mr. Assad’s rule.
At next week’s meeting of the United Nations General Assembly, heads of state and top diplomats are expected to discuss how to protect Idlib’s residents from Mr. Assad and, ultimately, end the civil war. President Recep Tayyip Erdogan of Turkey, who has opposed Mr. Assad and deployed Turkish troops to Idlib, is scheduled to speak at the annual forum on Tuesday, as is President Hassan Rouhani of Iran, the Syrian government’s most loyal ally.
President Trump will also address the world body that day. He has repeatedly threatened to withdraw American troops from Syria, where they are fighting the Islamic State in the country’s east. But in April, Mr. Trump for the second time ordered airstrikes to punish Mr. Assad for using chemical weapons on Syrian civilians. The Trump administration is also clinging to a mostly stalled peace process that was begun under President Barack Obama.
“The reality on the ground in Syria has drastically changed, and the United States’ strategy for Syria should shift as a result,” foreign policy scholars wrote this month in an analysis for the Brookings Institution.
There are few easy answers for the United States as it weighs how to shape a potential end game in a war that has killed at least hundreds of thousands of Syrians, has displaced millions more and has shattered the country into competing areas of control. Here are some of the main questions.
Can the U.S. force Mr. Assad to step down as Syria’s ruler?
No, and the writers of the Brookings analysis argued that the Trump administration must instead acknowledge that Mr. Assad has consolidated power and will not relinquish it anytime soon, if ever.
However, the United States can continue to try to push Mr. Assad and his allies to agree to terms by which he later hands over power to a successor. Mr. Assad’s opponents have for years accused his government — and notably its iron-fisted security forces and disproportionate hold on power of the Shiite Alawite minority — of leading to the radicalization of Sunnis and contributing to the spread of extremist groups like the Islamic State.
The Brookings analysts also said that the United States should do everything it can to stave off an offensive of Idlib and respond with airstrikes against Mr. Assad’s military whenever it uses barrel bombs or chemical weapons on the Syrian population.
“The Assad regime has explicitly made it clear that it intends to retake control of the country as a whole, and that includes strategically vital provinces like Idlib,” Ranj Alaaldin, one of the Brookings analysts, said Friday in an interview.
He said the announcement of the demilitarized zone was likely a way for Mr. Assad and his allies to reorganize for a later strike: “The U.S. now has a chance to ensure it is adequately prepared to respond if, and when, the agreement collapses.”
Does the demilitarized zone renew efforts for a negotiated resolution to Syria’s civil war?
Yes, for now. The Trump administration continues to call for a Geneva-based peace process between Mr. Assad’s government and moderate opposition leaders, brokered by Staffan de Mistura, a United Nations envoy.
Mr. Assad has had little incentive to participate because he is winning. But that could change if the United States, Russia, Iran, Turkey and other nations manage to use the time bought by the demilitarized zone to negotiate a route to an end state acceptable to Mr. Assad.
“One of the things that you will increasingly see from the United States government in the coming weeks and months ahead is a recommitment to the Geneva process,” Heather Nauert, the chief State Department spokeswoman, said at a news conference this week. “We see that as the only way forward.”
Last month, Defense Secretary Jim Mattis said the American goal “is to move the Syria civil war into the Geneva process, so the Syrian people can establish a new government that is not led by Assad, and give them a chance for a future that Assad has denied them.”
But, for the most part, the Trump administration has stopped talking about trying to remove Mr. Assad from office. And though the United States seeks a leading role in the peace process, in hopes of shaping the outcome, so do its rivals.
Russia’s intervention in September 2015 swung the fighting decisively in Mr. Assad’s favor, in part because the United States has not been willing to counterbalance Moscow’s military role in the civil war. Russia has sponsored its own peace process based in the Kazakh capital, Astana.
Iran has also played a major diplomatic role in Syria, and this month it hosted a meeting with Russia and Turkey to discuss a political settlement to end the civil war.
In any case, the Geneva process has had its critics. It has achieved little in the year since Lisa Roman, a Syria adviser during the Obama administration, described it as a “charade.”
“If we want to see greater stability in the years ahead, we need to change course,” Ms. Roman co-wrote in an essay.
What does the U.S. plan to do about Iran’s involvement in Syria?
There may not be much the United States can do, despite the Trump administration’s unalloyed hostility toward Iran.
The United States may seek to persuade Russia to push Mr. Assad to tell Iran to withdraw its forces from Syria. Iranian forces and Iranian-backed militias in Syria, including Hezbollah, are viewed both by the Trump administration and Prime Minister Benjamin Netanyahu of Israel as a serious threat to regional stability.
But few believe such an effort of diplomatic telephone will succeed.
“I think they are genuine in wanting to push Iran out of Syria, but I don’t think they’re realistic in trying to achieve it,” said Andrew Miller, who worked on Middle East issues on the National Security Council in the Obama administration.
“They’re relying on a specific play — driving a wedge between the Russians and the Iranians,” Mr. Miller said. “They want the Russians to bring the Syrians in and pressure the Assad regime to downsize their relationship with Iran.”
But the United States should not expect Mr. Assad to turn on Iran.
How will the situation in Idlib affect the war on the Islamic State?
It probably won’t. There are essentially two campaigns being waged in Syria, with the civil war largely centered in Syria’s western provinces and the fight against the Islamic State in the east.
There are an estimated 2,000 American troops in Syria’s east, mostly Special Operations forces that with a Kurdish-led militia are fighting the last remains of the Islamic State. That battle shows no immediate signs of ending, as the militants have slowly stopped trying to hold territory and instead are transforming into an insurgent group.
And since the Syrians, Russians and Iranians are also opposed to the Islamic State, they are unlikely to do anything to hinder the American effort there.
Will the U.S. maintain a military presence in Syria?
Yes, at least for the foreseeable future.
This month, the American military flew 100 Marines to Tanf, a small outpost in eastern Syria near the Iraqi border. The small deployment of troops was intended to signal to the Syrian government and its Russian and Iranian allies that the American military was digging in.
Tanf is more than 200 miles from Idlib. But the Russian military twice warned the Pentagon this month — on Sept. 1 and again on Sept. 6 — that it would attack what it said were Islamic State militants in the stretch of desert near the small outpost where American Special Operations forces have been training local militias.
At some point, Mr. Assad will undoubtedly have to address the American presence in northeastern Syria, where United States troops have built a constellation of bases and airfields.
In early September, a State Department envoy, James F. Jeffrey, told reporters in Washington that “the new policy is we’re no longer pulling out by the end of the year.”
He said he was “confident” that Mr. Trump was “on board” with the American military taking a more active role in Syria.
Edward Wong, Gardiner Harris and Thomas Gibbons-Neff reported from Washington. Ben Hubbard contributed reporting from Beirut, and Eric Schmitt and Mark Landler contributed reporting from Washington.