Members of the pro-Syrian government forces ride a tank in the Syrian border town of Albu Kamal, on Monday. Syria's army and loyalist militiamen on Sunday ousted the Islamic State from its last urban stronghold in the country. (AFP/Getty Images)

The Trump administration is expanding its goals in Syria beyond routing the Islamic State to include a political settlement of the country’s civil war, a daunting and potentially open-ended commitment that could draw the United States into conflict with both Syria and Iran.

With forces loyal to President Bashar al-Assad and his Russian and Iranian allies now bearing down on the last militant-controlled towns, the defeat of the Islamic State in Syria could be imminent — along with an end to the U.S. justification for being there.

U.S. officials say they are hoping to use the ongoing presence of American troops in northern Syria, in support of the Kurdish-dominated Syrian Democratic Forces (SDF), to pressure Assad to make concessions at United Nations-brokered peace talks in Geneva. The negotiations there are set to resume at the end of this month after sputtering along for more than three years without result.

Assad’s forces, with crucial aid from Iranian-sponsored militias, have regained control over much of the rest of the country in their separate war with Syrian rebels fighting to end the president’s autocratic rule.

An abrupt U.S. withdrawal could complete Assad’s sweep of Syrian territory and help guarantee his political survival — an outcome that would constitute a win for Iran, his close ally.

Syrians check the rubble of buildings on Nov. 14 following an air strike on the rebel-held Syrian town of Atareb. (Zein Al Rifai/AFP/Getty Images)

To avoid that outcome, U.S. officials say they plan to maintain a U.S. troop presence in northern Syria — where the Americans have trained and assisted the SDF against the Islamic State — and establish new local governance, apart from the Assad government, in those areas.

When political negotiations began in Geneva more than three years ago, the rebels — with some assistance from Western and Sunni Arab backers — controlled a hefty amount of Syria and were in a far better position to demand Assad’s removal as part of a settlement.

Russian air power and Iranian-allied ground forces, however, have sharply turned the situation to Assad’s advantage both on the battlefield and at the negotiating table. Russia and Iran have also indicated they plan to stay.

In addition to extending the U.S. presence in Syria, the administration is also seeking new cooperation with Russia. Earlier this month, President Trump and Russian President Vladi­mir Putin signed a joint statement backing the Geneva process. The two leaders spoke again by telephone Tuesday, just hours after Putin was photographed embracing Assad when the two met in the Russian resort of Sochi.

Russia, together with Iran and Turkey, is hosting its own political conference this week on Syria, a gathering that could lock in positions that would make U.S. objectives harder to achieve.

U.S. officials emphasized that an ongoing U.S. military presence in Syria is necessary to ensure that Islamic State remnants are mopped up and that repopulated communities are stabilized under local governance. “The fight with ISIS is not over,” one official said, using an acronym for the Islamic State. 

But the official, one of several who spoke on the condition of anonymity to discuss ongoing planning and initiatives, described the indefinite mission of U.S. forces as “twofold.”

The Islamic State’s original expansion was enabled by the vacuum of authority left by the Syrian civil war, the official said. “That vacuum was created by the lack of a legitimate political process,” and the militant group, or its successors, will fill it again if the “political aspect” is not resolved.

Asked last week how long U.S. troops would stay in Syria, Defense Secretary Jim Mattis said: “We’re not just going to walk away right now” before a political settlement is reached between Assad and the Syrian opposition. “We’re going to make sure we set the conditions for a diplomatic solution. . . . Not just, you know, fight the military part of it and then say good luck on the rest of it.” 

The official number of U.S. troops currently deployed to Syria is 503, sent to train and assist the SDF. The actual number is believed to be far higher, including hundreds of additional Special Operations forces, forward air controllers, artillery crews and others sent for months-long temporary deployments.

Mattis said there has been no decision on how many troops will remain. They will wait until “the Geneva process has cracked,” he said. “That doesn’t mean everyone stays there. That doesn’t mean . . . certain troops are leaving.”

Plans for a continuing troop presence indicate a shift in mission from defeating the Islamic State to a broader White House strategy aimed at countering Iranian influence, said Nicholas Heras of the Washington-based Center for a New American Security.

“The conditions are there for the counter-ISIS campaign to morph into a counter-Iran campaign,” Heras said. “The U.S. has no master plan to stay, but isn’t in any hurry to leave either,” he said. “By placing no timeline on the end of the U.S. mission . . . the Pentagon is creating a framework for keeping the U.S. engaged in Syria for years to come.”

In recent months, the United States and Russia have established a cease-fire zone in southwestern Syria near the borders with Israel and Jordan. The agreement requires opposition and government troops — along with their allies from the Iranian-backed Lebanese Hezbollah militia — to freeze in place. 

Israel has said that the agreement does not go far enough toward satisfying its concerns about Iran’s massively extended influence in Syria as a result of the civil war, which includes the deployment of Iranian Revolutionary Guard Corps military advisers and allied militias in large parts of the country controlled by the Assad government. Some of those forces are within six miles of Israeli-occupied territory in the Golan Heights.

Washington and Moscow also have negotiated deconfliction lines in the east, where government forces, aided by Russian airstrikes, have advanced against the Islamic State toward the border with Iraq in the same area where the SDF, with its American backers, is pushing south against the militants.

In angry statements last week, Russian Foreign Minister Sergei Lavrov and the Russian Defense Ministry accused the United States of directly aiding Islamic State forces that have come into conflict with the Syrian forces pushing toward the Iraqi border, and of allowing terrorists to escape from U.S.-backed offensives against them in both Syria and Iraq. The U.S. Defense Department just as angrily denied the charges.

The United States and Russia have chosen to emphasize different parts of the agreement between Trump and Putin, signed earlier this month when they met at an Asian regional conference, and committing their governments to support for the Geneva process.

The administration has hailed Russian support for negotiations that it believes will ultimately bring Assad’s departure. It is banking in part on provisions on the Geneva negotiating table that allow the Syrian diaspora, including millions of anti-Assad refugees who have fled the violence there, to vote in eventual elections to be held under international monitoring.

For its part, Russia has noted the agreement’s recognition of Syria’s sovereignty and territorial integrity. Lavrov last week pointed out that both Russia and Iran, unlike the United States, are in Syria at the invitation of its government. The Syrian government routinely denounces U.S. troops as “occupiers” and threatens to drive them out.

The agreement also calls for the eventual removal of foreign forces from Syria, but Russia has made clear that provision applies only to the southwest cease-fire zone, and the positioning of militias farther from the Israeli border.

Russia, on Assad’s behalf, has long insisted that the Geneva negotiations be held without preconditions — code for leaving open the door for Assad’s continuation in power. During his campaign, Trump appeared to agree, indicating that the United States could find common purpose with Assad and his allies in fighting against the Islamic State.

“Our priority is no longer to sit and focus on getting Assad out,” Nikki Haley, Trump’s U.N. ambassador, said in March. At the same time, Sen. John McCain (R-Ariz.) asserted that the new administration was headed toward a “Faustian bargain with Assad and Putin, sealed with an empty promise of counterterrorism cooperation.”