Terrorist groups - home based:
al-Nusrah Front: aim(s): overthrow Syrian President Bashar al-ASAD's regime, absorb like-minded Syrian rebel groups and, ultimately, establish a regional Islamic caliphate area(s) of operation: headquartered in the northwestern Idlib Governorate, with a minor in Halab Governorate; operational primarily in northern, western, and southern Syria; al-Nusrah's subunit Jund al-Aqsa operates in Idlib and Hama governorates; installs Sharia in areas under its control; targets primarily Syrian regime and proregime forces, some minorities, occasionally other Syrian insurgent groups, and Western interests; openly collaborated with core al-Qa'ida veteran and senior figures until supreme leader Fateh al-JAWLANI announced publicly in mid-2016 that formal ties with al-Qa'ida had been cut and al-Nusrah would henceforth operate under the name Jabhat Fateh al-Sham (Front for the Conquest of the Levant); JAWLANI's disaffiliation claim remained unsubstantiated as of early 2017, according to the US Government; engages in effective online and in-person recruitment campaigns in Syria; majority of members are Syrian, with many al-Qa'ida veterans from other jihad theaters; assessed in mid-2016 to have at least 6,000 active fighters
Islamic State of Iraq and the Levant (ISIL): aim(s): replace the Syrian Government with an Sunni Islamic state and implement ISIL's strict interpretation of Sharia area(s) of operation: maintains extensive networks and an operational presence throughout the country, despite losing large swathes of territory since early 2016; ISIL had lost most of its control in its defacto capital, the city of Ar Raqqah, by mid-2017; continues to operate bases in the Ar Raqqah area and along the Syria-Iraq border; thousands of combatants target Syrian and Russian Government interests, religious and ethnic minorities, and all groups or governments that oppose ISIL's hardline Sunni jihadist ideology, including perceived Sunni rivals; exploits natural resources, especially oil and wheat, and levies taxes and fees on companies and individuals in areas under its control; responsible for millions of Syrians fleeing their homes, including the estimated 5 million who had left Syria by early 2017; fighters have ransacked and demolished numerous ancient sites that pre-date Islam, denouncing them as idolatrous; in May 2015, ISIL overran the ancient city of Palmyra, a UNESCO World Heritage site famed for its well-preserved Graeco-Roman ruins, and went on to destroy its best known structures; has used mustard and chlorine gas against civilian and military targets in Syria, where allies continue to work together to dismantle its chemical weapons production plants; dozens of key leaders have been killed since early 2016, putting ISIL's highly decentralized structure and spawling network of regional affiliates to the test; senior leader Gulmurod KHALIMOV, a former Tajik military officer serving as ISIL's chief recruiter, remains based in Syria; ISIL's chief cleric, Turki al-BINALI, was killed on 31 May 2017 during an airstrike in Al Mayadin, Dayr az Zawr Governorate, near the border with Iraq; al-BINALI's recorded lectures and other propaganda were central in recruiting foreign fighters

Terrorist groups - foreign based:
Abdallah Azzam Brigades (AAB): aim(s): disrupt and attack Shia Muslim and Western interests in Syria area(s) of operation: remains operational; conducts attacks against primarily Shia Muslim organizations and individuals, including Hizballah members, and Westerners and their interests
al-Qa'ida (AQ): aim(s): support al-Nusrah Front's efforts to overthrow President Bashar al-ASAD's regime and, ultimately, establish a regional Islamic caliphate area(s) of operation: operational primarily in Idlib Governorate, with established networks and operating paramilitary training camps; likely continues to collaborate closely with al-Nusrah Front leaders, despite public claims of severing ties; majority of members are not Syrian nationals
Ansar al-Islam (AAI): aim(s): remove Syrian President Bashar al-ASAD from power and install Sharia area(s) of operation: operationally active in Syria since 2011; remained operational in Aleppo as of late 2016; launches attacks on Syrian Government and security forces and pro-Syrian Government militias; some AAI factions combat ISIL, while others are aligned with ISIL
Hizballah: aim(s): preserve Syrian President Bashar al-ASAD's regime area(s) of operation: operational activity throughout the country since 2012; centered on providing paramilitary support to President Bashar al-ASAD's regime against armed insurgents; tens of thousands of fighters remained active in Syria as of 2017; thousands of fighters have died on the Syrian battlefield
Kata'ib Hizballah (KH): aim(s): preserve Syrian President Bashar al-ASAD's regime area(s) of operation: deploys combatants to Syria to fight alongside Syrian Government and Lebanese Hizballah forces
Kurdistan Workers Party (PKK) (Kongra-Gel): aim(s): establish Kurdistan, which comprises territory in northern Syria area(s) of operation: operational in the north combating ISIL, primarily in the Kurdish-populated region known as Rojava and Syrian Kurdistan; Salih MUSLIM Muhammad leads Kurdistan Workers Party's Syrian wing, the Syrian Kurdish Democratic Union Party (PYD); majority of fighters inside Syria are Syrian Kurds, along with Kurds from Iran, Turkey, and Iraq
Mujahidin Shura Council in the Environs of Jerusalem (MSC): aim(s): enhance its networks in Syria and, ultimately, destroy the state of Israel area(s) of operation: maintains limited networks for operational planning against Israel, logistics, transferring funds, and smuggling fighters and arms through Syria from the Gaza Strip and Libya to be used against Israel; by 2017, the majority of veteran members had defected to join other groups
Palestine Liberation Front (PLF): aim(s): enhances its networks and, ultimately, destroy the state of Israel and establish a secular, Marxist Palestinian state with Jerusalem as its capital area(s) of operation: maintains a recruitment and limited training presence in many refugee camps
PFLP-General Command (PFLP-GC): aim(s): preserve Syrian President Bashar al-ASAD's regime area(s) of operation: maintains a political base in Damascus; fighting since early 2012 alongside President al-ASAD's forces and Hizballah in areas where anti-regime paramilitary groups are active; currently, preserving al-ASAD's government is the group's most pressing priority; receives funds and training from the regime
Popular Front for the Liberation of Palestine (PFLP): aim(s): enhance its recruitment networks in Syria area(s) of operation: maintains a recruitment and limited training presence in several refugee camps