Key internal actors
Syrian Government — President Bashar al-Assad, of Shi'ite offshoot Alawite minority, dubs all opponents, civilian or armed, "terrorists;" indiscriminately kills civilians, as well as armed opposition.
Relatively Moderate and Islamic Nationalist Opposition — Includes Western-backed Free Syrian Army, countless local militias seeking Assad's ouster. Mainly Sunni. At times, has sided with hardline Islamists when battlefield circumstances have dictated; but threaten further cooperation if U.S. doesn't provide more backing.
Islamist Opposition — Includes hardline Islamist forces Ahrar al-Sham and al-Qaida affiliate Jabhat al-Nusra. Seeks to overthrow Assad; works at times with moderate opposition.
Kurdish Forces — Mainly fighting Islamic State, but have clashed in past with moderate and Islamist rebels; once Assad launched recent Aleppo offensive, moved quickly to grab FSA and Islamist-held towns in northern Syria. Seeks to unite Kurdish enclaves along Turkish border.
Islamic State — Jihadist insurgency, fights everyone. Seeks to establish caliphate.
Key external actors
United States — Leads international coalition fighting Islamic State. Backs Kurds in their fight east of the Euphrates River against the Islamic State group and some moderate and Islamic nationalist opposition forces.
Turkey — Part of the anti-IS coalition, but critical of U.S. insistence on focusing only on IS and not on the ouster of Assad. Opposed to Kurdish self-rule ambitions, and now shelling Kurdish fighters.
Saudi and other Sunni Gulf States — Part of anti-IS coalition; focused also on removing Assad, deepening regional Sunni/Shi'ite divide.
Russia — Backs Assad government and has formed a battlefield alliance with the Kurds. Says its fight is against IS and other "terrorists," but has focused its military intervention on the moderate opposition to Assad.
Iran — Shi'ite-led government backs Assad, also worsening sectarian divides.
Hezbollah — Lebanese Shi'ite militia backs Assad government, a longtime patron, another sectarian player.
