IRAQ - Sadr's Background.

Though in his early 30 and a low-ranking mullah, Sadr comes from a prominent Shi'ite religious family. His sources of appeal are: fierce nationalism, a shrewd sense of when to confront the occupying power and when to lie low, and adherence to the hierarchical order of the Shi'ite sect, led by Grand Ayatullah Ali Sistani whose opinion or fatwa (decree) must be accepted by all those below him. Muqtada's father, Ayatullah Muhammad-Sadeq al-Sadr, and two elder brothers were assassinated outside a mosque in Najaf in February 1999 by henchmen of Saddam's dictatorship. Muqtada's uncle, Grand Ayatullah Muhammad-Baqer al-Sadr, was a co-founder of al-Da'wa al-Islamiya movement in the 1960s and was executed in 1980 by Saddam dictatorship along with his famed sister.

Muqtada's father had defied Saddam by issuing a fatwa (religious decree) calling on Shi'ites to attend Friday prayers in mosques. Saddam, paranoid about large Shi'ite gatherings and having had his army's tanks paint the slogan "no more Shi'ism", feared these would suddenly turn violently against his regime. Muqtada then went underground - just as he did recently in the face of the US "surge" plan - resurfacing only after the Ba'thists fell in April 2003; and Saddam City, a slum of Baghdad with nearly 2m Shi'ites, was renamed Sadr City.

The Sadrs, however, had all along been Arab nationalists opposed to those Shi'ite imams who were of Persian or Azeri origin - such as Grand Ayatullah Abolqassem al-Khou'i who originated from Azerbaijan and who died in 1992 under house arrest in Najaf, or Grand Ayatullah Sistani who was born Iranian and who succeeded Khou'i and followed Khou'i's "quietist school" of Shi'ite Islam (at odds with the "interventionist school" of those involved in politics and day-to-day government). The Sadrs also had the Hakims as rival because the latter maintained close links to Iran's Shi'ite theocracy.

Sadr's father was the mentor of Hassan Nasrallah, now the secretary-general of Lebanon's Iran-sponsored Shi'ite guerrilla/political movement Hizbullah. Although formed in Najaf as an Arab nationalist, like the young Sadr, Nasrallah eventually was lured by the theocracy of Iran and now is the chief representative of Iran's Supreme Leader Ayatollah Ali Khamenei in Lebanon; as such, Khamenei is the Supreme Leader of the entire world because in Ja'fari Shi'ite terms in the way he interprets, Iran's theocracy is only a founding part of a universal Ja'fari theocracy - its rival now is the Neo-Salafi "Caliphate" in Iraq. Although these two extremes in Islam are temporarily in some kind of alliance against the US, in the future they will be arch-enemies as they simply do not recognise each other's legitimacy.

After the invasion, US forces brought from London to Najaf Abdel-Majid al-Khou'i, a son of the grand ayatullah who fled to the British capital as Saddam crushed a Shi'ite rebellion in southern Iraq in March 1991. Khou'i was stabbed to death in the Imam Ali Shrine of Najaf in April 2003 and his body was dragged in public along the road to the Najaf home of Muqtada - who was later charged with ordering the murder of Khou'i.

Sadr was among those suspected of involvement in the murder in front of the Imam Ali Shrine of Grand Ayatullah Muhammad-Baqer al-Hakim, founder of SCIRI, in August 2003 - although his death was also blamed on the Neo-Salafi terrorist Abu Mus'ab al-Zarqawi who was killed in a US air strike in June 2006. Abdul-Aziz al-Hakim, then head of SCIRI's militia arm Badr, succeeded his elder brother in leading the Supreme Council. His rivalry with Sadr has become more tense in recent months.

Sadr has consistently opposed the US occupation, as well as most of the other Shi'ite political groups in Iraq. When L Paul Bremer, the US viceroy in Iraq, banned his magazine al-Hawza al-Natiqa ('The Vocal Seminary') in April 2004 and US soldiers fired on his followers peacefully against the publication's closure, Sadr called for "armed resistance" to the occupiers. Uprisings spread from Sadr City to the holy cities of Najaf and Karbala' as well as four other cities to the south. More than 540 civilians died in the resulting battles. Since the US forces were also battling Sunni/Neo-Salafi insurgents in Falluja, Bremer let the ban on the magazine lapse and dropped plans to arrest Sadr in the Khou'i murder case.

Later, Sadr fell in line with the wishes of Sistani to see all Shi'ite religious groups gather under the UIA umbrella to contest parliamentary elections. By so doing, in the face of US hostility, Sadr gave protective political cover to his group and Jaysh al-Mahdi.

When the Pentagon mounted its latest security plan for Baghdad on Feb. 13 - aiming to crush both Sunni and Shi'ite militias - Sadr ordered Jaysh al-Mahdi to get off the streets and hide its weapons. Sadr then went into hiding - some say in Qom and others claim he is still in Iraq. In a message to the Iraqis on the eve of the fourth anniversary of Saddam's fall, Sadr coupled his order to Jaysh al-Mahdi to intensify its campaign to expel the foreign troops with a call to the Iraqi security forces to join the struggle to defeat "the arch enemy - America".