A look at the forces converging on Islamic State-held Raqqa

BEIRUT – A major assault on the Islamic State group's self-proclaimed capital of Raqqa is expected to begin in the coming weeks, but various military forces eyeing the northern Syrian city are bitterly divided.

Here's a look at the players:

SYRIAN KURDS

The U.S.-backed Syria Democratic Forces — a Kurdish-led alliance that includes Arab tribesmen and Christian militias — is the most effective ground force battling the Islamic State group in Syria.

With the help of American advisers and U.S.-led coalition airstrikes, the SDF has captured much of northern Syria and since November has been working to isolate the city. But the main Kurdish militia in the group is seen as a terrorist organization by Turkey, a NATO member which also has its sights on Raqqa.

TURKEY

Ankara sent ground troops into northern Syria in August to help Syrian opposition forces drive Islamic State militants from the border and curb the advance of Kurdish forces, which it sees as an extension of the Kurdish insurgency in southeastern Turkey.

The Turkey-backed forces recently captured the former IS stronghold of al-Bab after three months of grueling fighting that killed scores of Turkish troops and allied Syrian fighters.

Turkey's President Recep Tayyip Erdogan said last month that his troops and allied Syrian fighters would eventually march on Raqqa, and his prime minister has warned that an SDF takeover of Raqqa would harm relations between Ankara and Washington.

SYRIAN GOVERNMENT

Syrian government forces have also been on the offensive against the IS group in northern Syria, capturing dozens of villages from the extremists in recent weeks.

The troops are backed by battle-hardened members of Lebanon's Hezbollah group and operate under the cover of Russian and Syrian airstrikes. Syrian President Bashar Assad has suggested that Raqqa could be their next target, but his troops are overstretched and lack the resources.

Syria's government is fiercely opposed to any involvement by Turkey, which is a leading sponsor of opposition forces battling to overthrow Assad.

U.S. AND RUSSIAN FORCES

Around 500 U.S. special operations forces are in Syria helping to organize, advise and assist local forces, mainly the SDF. The U.S. military has also provided a small number of armored vehicles to the Syria Arab Coalition, part of the SDF, for better protection as they get closer to Raqqa.

Defense Secretary Jim Mattis on Monday gave the White House a plan to "rapidly defeat" the Islamic State group, a strategy that could potentially deepen U.S. military involvement in Syria.

That may elevate the risk of a confrontation with Russia, which has been waging an intensive air campaign in support of Assad's forces since 2015. A U.S. general said Wednesday that a Russian airstrike in northern Syria hit the Syria Arab Coalition, adding than an unspecified number of American military advisers were a few kilometers (miles) away. Russia denied responsibility.