Over the course of the U.S. presidential campaign, Donald Trump changed his mind on many issues. But he’s been consistent on one foreign policy question: he wants to end American support for Syrian opposition groups fighting Bashar al-Assad’s regime. Trump argues that the United States should expend all of its efforts on fighting Islamic State instead.  "I’ve had an opposite view of many people regarding Syria,” Trump told the Wall Street Journal on Nov. 11, in his first interview after he won the White House. “My attitude was you’re fighting Syria, Syria is fighting ISIS, and you have to get rid of ISIS. Russia is now totally aligned with Syria, and now you have Iran, which is becoming powerful, because of us, is aligned with Syria. … Now we’re backing rebels against Syria, and we have no idea who these people are.”  Even if Trump goes ahead with his threat to cut off aid to Syrian rebels fighting the Assad regime – especially those supported by a covert CIA program which provides training and anti-tank missiles – the president-elect will face another major test of his Syria policy soon after he’s inaugurated on Jan. 20. The United States is supporting two military campaigns simultaneously in Syria: one against Assad’s government and the other against Islamic State. Trump has made clear that he doesn’t view the fight against Assad as a U.S. priority. But will Trump continue a separate Pentagon support and training program for the Syrian Democratic Forces, a coalition of rebel groups, which is leading a ground offensive to oust Islamic State from the city of Raqqa, capital of its self-proclaimed caliphate?  That campaign started on Nov. 6 with a mobilization of about 30,000 rebels to encircle Raqqa and cut it off from all sides, to deny Islamic State the ability to resupply weapons and fighters. The battle to push the jihadists out of Raqqa could take months. If it falters under a fledging Trump administration, Islamic State would have a safe base from which it would unleash new attacks in Syria and Iraq, and against the West.  U.S. military planners pushed for the Raqqa offensive to start soon after the long-awaited invasion to recapture Iraq’s second-largest city, Mosul, from the militants began in mid-October. Pentagon officials say they fear that Islamic State operatives, including some who fled the Mosul offensive, will use Raqqa to plot attacks against Western targets. “There’s a sense of urgency about what we have to do here because we’re just not sure what they’re [jihadists] up to, and where, and when,” the top U.S. military commander in Iraq, Lt. General Stephen Townsend, said at a news conference on Oct. 26  in Baghdad. “But we know that this plot planning is emanating from Raqqa.”  Trump says he wants to avoid direct U.S. involvement in the Syrian conflict, which has expanded into a regional proxy war. Russia and Iran, along with allied militias like Lebanon’s Hezbollah, are helping Assad consolidate control and recapture territory he lost to the rebels and jihadist groups. Assad and his backers have rarely fought directly against Islamic State, which controls Raqqa and other parts of eastern Syria. Turkey, Saudi Arabia, Qatar and the United States are backing various rebel factions that are fighting Assad and his allies, and, at times, Islamic State.  Under Barack Obama’s administration, the CIA has funneled up to $1 billion a year in weapons, including light arms, ammunition and anti-tank missiles, to Syrian rebel groups fighting the Assad regime that were deemed moderate by U.S. officials. But some of these rebels have been forced into battlefield alliances with jihadists, including al Qaeda affiliated groups.  While the offensive against Islamic State in Raqqa began in the waning days of the Obama administration, it needs support from the incoming Trump administration to bear fruit. But the Raqqa operation is already alienating American allies, especially Turkey, which is critical of the Syrian Democratic Forces. The SDF is a coalition of Kurdish, Sunni Arab, Christian and Turkmen rebel groups that is anchored by the People’s Protection Units (known by its Kurdish acronym, YPG), which includes thousands of Syrian Kurdish fighters.  Turkish leaders view the YPG and other Syrian Kurdish groups as allies of the Kurdistan Workers’ Party (known as the PKK), which has waged an insurgency against the Turkish government since the 1980s, seeking autonomy for Kurdish areas. Turkish President Recep Tayyip Erdogan insists that Washington must not allow the YPG to take a leading role in expelling Islamic State from Raqqa, a largely Sunni Arab city.  During the presidential campaign, Trump argued the United States should arm and help Kurdish factions, both in Iraq and Syria. “I’m a big fan of the Kurdish forces,” he said in July. If Trump follows through on his praise of the Kurds, that would be good news for the SDF and its largest militia, the YPG.  But once in office, Trump would also have to balance the objections of allies like Turkey and Erdogan, its increasingly autocratic president. Among his first top appointments, Trump named Michael Flynn, a retired general and former head of the Defense Intelligence Agency, as his national security adviser. Flynn, who once worked as a paid lobbyist for a prominent Turkish businessman, has expressed strong support for Erdogan’s government and argued that Washington should be more sympathetic to its concerns.  In late August, Turkey sent several hundred of its special forces into Syria, and began carrying out air strikes to help rebel factions allied with Ankara consolidate control of territory near the Turkish-Syrian border. The Turkish-backed rebels have fought both Islamic State jihadists and occasionally the U.S.-backed YPG militia.  In October, Erdogan said he told Obama in a phone call that Turkey was capable of ousting Islamic State from Raqqa on its own. Other Turkish officials argued that the campaign to retake Raqqa should not begin until Iraqi forces complete their offensive against Islamic State in Mosul, which has slowed in recent weeks.  But U.S. officials are keen to isolate Raqqa and use Syrian forces to encircle it, mainly because of worries about Islamic State operatives fleeing from Mosul and plotting new attacks against the West. That concern is genuine because the jihadist group – even as it was weakened over the past year, after intensive U.S.-led bombing and defeats by its opponents in Iraq and Syria – has shown a significant ability to adapt and inflict new terror.  In the coming months, Islamic State will find new ways to endure an American-orchestrated offensive on Raqqa. It will try to take advantage of the change in U.S. administration. And once he’s in office, Trump will discover that fighting and containing Islamic State inevitably means wading into Syria’s complicated war.  