BEIRUT – U.S.-backed Syrian forces launched their attack on the Islamic State group's de facto capital of Raqqa in northern Syria, just as the jihadist group is making its last stand in Mosul in neighboring Iraq.
The Raqqa operation has been a long time coming. The Syrian Democratic Forces have had to fight through miles of Islamic State territory to reach the city and secure three dams along the Euphrates River. Tensions with Turkey have also slowed the pace of the advance. Here's a closer look at what the coming battle means:
WHO IS LEADING THE OFFENSIVE?
The Kurdish-dominated Syrian Democratic Forces, estimated at 50,000 by the U.S.-led coalition, have emerged as one of the principal players in the many-sided civil war. They are recognized by the U.S. as one of the most effective fighting forces against IS and have captured large parts of northeastern Syria from the extremists.
The force is dominated by the Kurdish Party of Democratic Unity, or PYD, which aims to defend Kurdish areas of Syria. Despite occasional flare-ups, the PYD has had a tacit nonaggression pact with the Syrian government since the start of the civil war, and is seen by some rebels as a quiet ally of President Bashar Assad, accusations the PYD denies.
WHAT IS THE U.S. ROLE?
The U.S. has provided essential military and diplomatic support to the SDF. In the run up to the battle for Raqqa, the Trump administration said it would begin supplying the Kurdish elements of the SDF with heavy weaponry, much to Turkey's displeasure. It is already understood to have hundreds of special forces operators embedded with the SDF in what the Pentagon says are advisory roles. And beyond providing daily artillery and air support, the U.S. also dropped SDF fighters, U.S. commandos and weapons behind IS lines in a daring raid in March that helped free the stronghold of Tabqa from the jihadists.
WHAT ARE TURKEY'S OBJECTIONS?
Turkey views the PYD as an extension of the Kurdish insurgency raging in its southeast and often speaks of the PYD and IS as similar threats. Turkish forces and thousands of allied Syrian opposition fighters launched their own offensive in northern Syria in 2016, clashing with both the PYD and IS.
In April, Turkey struck Kurdish positions in Syria and Iraq, killing at least 20 fighters. It prompted the U.S. to parade its forces in Kurdish areas to discourage further conflict.
HOW SOON UNTIL RAQQA IS FREED FROM IS?
If Mosul is any indication, the battle for Raqqa will be a long and grinding one. Iraqi forces have been tied up in Mosul since October, where they have faced stiff resistance in the form of suicide car bombs, rocket attacks and booby-trapped buildings. Raqqa is much smaller than Mosul, but even the battles for Manbij and Tabqa — towns in northwest Syria on the SDF's route to Raqqa — took weeks to complete.
Prolonged combat will expose civilians trapped in Raqqa to great peril. Already, the international coalition is facing accusations of striking nonmilitary targets across Syria and Iraq, killing hundreds of civilians. In May, the Pentagon admitted to carrying out a strike in Mosul that killed at least 105 civilians and two IS fighters.
WOULD THE LOSS OF RAQQA MEAN THE END OF IS?
Losing Raqqa would deal a major blow to the extremist group. The city is the seat of power for its self-described caliphate and has been home to top IS leaders. It is also where the militants are believed to have plotted attacks in the West, including the 2015 assault on Paris.
But IS already has begun preparing its followers for the potential loss of territory, shifting its leadership and resources to the eastern Syrian city of Deir el-Zour. It is currently contesting that city with the Syrian government.
The jihadists also are likely to shift back to their insurgent roots. As forces close in on Raqqa, many fighters are expected to melt into the civilian population, with some forming "sleeper cells" that could hatch new attacks.
WHAT ABOUT SYRIA'S CIVIL WAR?
After six years of fighting, President Bashar Assad has retained control of Syria's five largest cities and its coast. But the economy is in tatters and half the country's population is displaced. The cost of rebuilding is expected to run in the hundreds of billions of dollars. Battles are continuing on several fronts.
Assad and his allies have always prioritized fighting Syrian rebels so long as there have been other forces to battle with the Islamic State group. But with the western backbone under their control, pro-government forces have shifted their attention to the jihadist group, and most importantly, to Deir el-Zour.
That campaign has already threatened to ignite conflict with the coalition against the Islamic State. Two of the government's three routes to Deir el-Zour intersect with rebel and Kurdish forces supported by the U.S. In May, the U.S. struck a column of pro-government forces it judged were moving threateningly toward its local allies in the eastern Syrian desert. Several government soldiers were killed.