A Shiite militia formed in Iran in the early 1980s with the aim of toppling Saddam Hussein from exile. Thought to number up to 20,000 highly trained men, they fought on the side of Iran during the 1980-88 Iran-Iraq war. Once led by Abdul Aziz al-Hakim, who now heads the Supreme Council for the Islamic Revolution in Iraq, part of Iraq's ruling Shiite coalition. The group is still believed to be fully formed and armed.
The Peshmerga, a Kurdish word literally meaning "those ready to die", was created in 1946 to fight for an independent Kurdish state. The force numbers up to 140,000 with loyalties divided between Kurdistan's two main political groups, the Kurdish Democratic Party and the Patriotic Union of Kurdistan. Around 20,000 peshmerga have been folded into Iraq's Army, but they are largely based in the Kurdish region. Officially, the militia has been disbanded, but most say it could quickly be reformed.
Formed after Saddam's overthrow in April 2003, the Mehdi army is loyal to Moqtada al-Sadr, a fiercely outspoken, 33-year-old Shiite cleric who is popular among Iraq's poor, urban Shiite majority. Sadr led two rebellions against United States and British forces in 2004. The Mehdi army numbers around 10,000, but there are thousands more who are loosely affiliated with it and could be called upon to fight. During 2005 the Mehdi army and Badr clashed on several occasions.
Sunni militant groups
There are a range of nationalist Sunni militant groups operating in Iraq, several loosely affiliated, others operating alone. They formed in the wake of Saddam's overthrow with the hope of driving US-led forces out of Iraq and have been responsible for many bombings, kidnappings and assassinations.
Some profess loyalty to Saddam, others have ties to the militant group al Qaeda in Iraq, led by the Jordanian Abu Musab al-Zarqawi. This month a group of Sunnis formed a militia called the Anbar revolutionaries, which is designed to oppose Shiite and Kurdish militias and foreign militant groups such as Zarqawi's.
According to the US military, Iraq's security forces now number 220,000, including police, border guards, army battalions and a small special operations unit, all trained to varying degrees of ability. They are backed up by more than 130,000 US troops and around 20,000 others.