LONDON: Here is a breakdown of the main forces fighting Islamic State jihadists in Iraq and Syria, after British lawmakers on Wednesday voted to join the US-led bombing campaign in Syria:
Syrian and Iraqi armies
SYRIA: The Syrian army numbered 178,000 troops in 2015, according to the International Institute for Strategic Studies (IISS). In its fight against rebels and jihadists, it relies on militias, which claim 150,000 to 200,000 members.
IRAQ: The army counts 177,600 men, according to the IISS.
Since September, Baghdad has US F-16 fighter jets at its disposal. For ground forces, Iraq depends heavily on Shiite militias, notably the Popular Mobilization units (Hashed al-Shaabi) and Sunni tribal units.
Kurdish forces and rebel militias
Kurds have defended their own territory from the IS, backed by raids by a US-led coalition with Syria’s Kurdish People’s Protection Units (YPG) in the north and northeastern Syria, and peshmerga in northern Iraq.
Elsewhere in Syria, the armed opposition is fractured between a variety of moderate and Islamist rebel groups, including the powerful Ahrar al-Sham faction in north and northwestern Syria, the Army of Islam near Damascus, and the Southern Front in Daraa province.
Some of those forces have occasionally allied with Al-Qaeda affiliate Al-Nusra Front, an IS rival.
The US-led international coalition has been conducting air strikes in Iraq since September 2014 at Baghdad’s request, and in Syria, where it has publicly refused to collaborate with the Damascus authorities.
The coalition comprises around 60 countries, including Britain, France, Syria’s Arab neighbors and Turkey, as well as since late September Tunisia, Malaysia and Nigeria.
Five countries — the US, France, Canada, Australia and Jordan — have been taking part in air strikes in both Syria and Iraq. Britain will be the sixth.
Others are taking part in strikes in Syria but not Iraq: Saudi Arabia, Bahrain, United Arab Emirates and Turkey, or in Iraq but not Syria: Denmark and the Netherlands.
FRANCE: is stepping up its air strikes in Syria after the November 13 terrorist attacks in Paris claimed by the IS. It has mobilized 3,500 soldiers, and deployed its flagship aircraft carrier Charles de Gaulle to the eastern Mediterranean, more than tripling its strike capacity.
TURKEY: launched its first air strikes with the coalition on August 28, and has authorized the US to use its strategic base at Incirlik.
Canada plans to withdraw its combat aircraft but reinforce the 69 special forces troops currently posted in Iraqi Kurdistan.
Germany has sent around 100 soldiers to train Kurdish troops and is to add 1,200 to the fight in Syria.
RUSSIA: A key ally of the Damascus regime, Moscow began launching air strikes on September 30 in Syria, after boosting its military presence over the summer.
IRAN: The Shiite power has committed its elite troops, the Revolutionary Guards, in Syria. In all some 7,000 soldiers have been sent to Syria and Iraq.
LEBANON: The powerful Shiite militia Hezbollah has committed between 5,000 and 8,000 fighters to Syria where they operate alongside the army.