Foreign involvement in the Syrian civil war

Most parties involved in the war in the Syrian civil war received various types of support from foreign countries and entities based outside Syria. The conflict in Syria was widely described as a series of overlapping proxy wars between the regional and world powers, primarily between the United States and Russia as well as between Iran and Saudi Arabia.

The Syrian Ba'athist regime under President Bashar al-Assad was politically and militarily supported by Iran and Russia, and actively supported by the Lebanese Hezbollah group, the Syrian-based Palestinian group PFLP-GC, and others. From 30 September 2015 until the war's end, Russia openly deployed its military assets in Syria and waged an intensive air campaign against anti-government forces in Syria, in support of and at the request of the Assad government. The military activity of Russia in Syria was criticized by the US and its regional allies; Turkey overtly clashed with the Russian military in November 2015 over the alleged violation of its airspace by a Russian plane, as well as over Russia′s bombardment of the areas held by anti-government forces supported by Turkey.

The Syrian opposition, politically represented by the Syrian National Coalition, received financial, logistical, political and in some cases military support from major Sunni states in the Middle East allied with the U.S., most notably Saudi Arabia, Qatar, and Turkey. From the early stages of the conflict in Syria, major Western countries such as the U.S, France, and the UK provided political, military and logistic support to the opposition and its associated rebel groups in Syria.

The Syrian Democratic Forces of the Executive Council (Rojava), the government of Rojava, received military and logistic support from some NATO countries, the US in particular. Since July 2015, it has been attacked by the Turkish military and the Turkish-backed Free Syrian Army, leading to the Turkish occupation of northern Syria.

From 2014 until October 2017, a significant part of Syria's territory was controlled by the Islamic State of Iraq and the Levant (ISIL), an entity internationally recognised as terrorist, a number of Western and other countries, most notably the U.S., Russia, Britain, and France, have participated in direct military action against ISIL in both Syria and Iraq.