In Syria, the UN Disengagement Observer Force (UNDOF) has operated in the Golan between Israel and Syria since 1974 to monitor the ceasefire following the 1973 Arab-Israeli War and supervise the areas of separation between the two countries; UNDOF has about 1,000 personnel 

multiple actors have conducted military operations in Syria in support of the ASAD government or Syrian opposition forces, as well in pursuit of their own security goals, such as counterterrorism and border security; operations have included air strikes, direct ground combat, and sponsoring proxy forces, as well as providing non-lethal military support, including advisors, technicians, arms and equipment, funding, intelligence, and training:

pro-ASAD elements operating in Syria have included the Syrian Arab Army, Lebanese Hizballah, the Iranian military, Iranian-backed Shia militia, and Russian forces; since early in the civil war, the ASAD government has used Lebanese Hizballah and Iranian-backed irregular forces for combat operations and to hold territory; since 2011, Iran has provided military advisors and combat troops from the Iranian Revolutionary Guard Corps (IRGC), as well as intelligence, logistical, material, technical, and financial support; it has funded, trained, equipped, and led Shia militia/paramilitary units comprised of both Syrian and non-Syrian personnel, primarily from Afghanistan, Iraq, and Pakistan; Russia intervened at the request of the ASAD government in 2015 and has since provided air support, special operations forces, military advisors, private military contractors, training, arms, and equipment; Iranian and Russian support has also included assisting Syria in combating the Islamic State of Iraq and ash-Sham (ISIS) terrorist group

Turkey has intervened militarily several times since 2016 to combat Kurdish militants and ISIS, support select Syrian opposition forces, and establish a buffer along portions of its border with Syria; Turkey continues to maintain a considerable military presence in northern Syria; it has armed and trained militia/proxy forces, such as the Syrian National Army, which was formed in late 2017 of Syrian Arab and Turkmen rebel factions in the Halab (Aleppo) province and northwestern Syria

the US and some regional and European states have at times backed Syrian opposition forces militarily and/or conducted military operations, primarily against ISIS; the US has operated in Syria since 2015 with ground forces and air strikes; the majority the US ground forces are deployed in the Eastern Syria Security Area (ESSA, which includes parts of Hasakah and Dayr az Zawr provinces east of the Euphrates River) in support of operations by the Syrian Democratic Forces against ISIS, while the remainder are in southeast Syria around At Tanf supporting counter-ISIS operations by the Syrian Free Army opposition force; the US has also conducted air strikes against Syrian military targets in response to Syrian Government use of chemical weapons against opposition forces and civilians, and since October 2023, against facilities in eastern Syria associated with Iran’s IRGC and affiliated militias in response to attacks by Iran-backed militias on US forces in Syria and Iraq; in addition, France, Jordan, Qatar, Saudi Arabia, and the UK have provided forms of military assistance to opposition forces and/or conducted operations against ISIS, including air strikes

Israel has conducted hundreds of military air strikes in Syria against Syrian military, Hizballah, Iranian military, and Iranian-backed militia targets

the Syrian Democratic Forces (SDF), a coalition of forces comprised primarily of Kurdish, Sunni Arab, and Syriac Christian fighters; it is dominated and led by Kurdish forces, particularly the People’s Protection Units (YPG) militia; the SDF began to receive US support in 2015 and as of 2024 was the main local US partner in its counter-ISIS campaign; the SDF has internal security, counterterrorism, and commando units; Turkey views the SDF as an extension of the Kurdistan Workers’ Party (PKK), a US-designated terrorist organization 

the ISIS terrorist group lost its last territorial stronghold to SDF forces in 2019, but continues to maintain a low-level insurgency inside Syria; in addition, the SDF holds about 10,000 captured suspected ISIS fighters in detention facilities across northern Syria, including 2,000 from countries other than Iraq and Syria

the Hay'at Tahrir al-Sham (HTS; formerly known as al-Nusrah Front) terrorist organization is the dominant militant group in northwest Syria and has asserted considerable influence and control over the so-called Syrian Salvation Government in the Iblib de-escalation zone and the Aleppo province (2024)