He is a strange figure to be targeted as the number one enemy of the US in Iraq. Four years ago, few had heard of the Shia nationalist cleric Muqtada al-Sadr inside or outside Iraq. Even somebody as suspicious as Saddam Hussein, who murdered his father and two brothers, did not think he would play any role in the coming crisis.
Now he holds the future of Iraq in his hands. He has far more popularity and legitimacy than many of the pro-American Iraqi leaders cowering in the Green Zone. He is seen by millions of Shia in Baghdad and across southern Iraq as their spiritual and national leader. Rightly or wrongly, he is feared by Sunnis as their nemesis, a physical symbol that they are battling for their existence in Iraq.
He has now become part of the White House's demonology in Iraq. At one time the US believed that Saddam Hussein was responsible for all its problems in Iraq - problems that would be resolved once he was overthrown. Today Sadr, a 32-year-old cleric in his black robe with fierce, staring, dark eyes, is denounced as the fomenter of sectarian warfare.
Many Iraqi leaders never leave the Green Zone. Sadr has never entered it. He has a cult-like following. He controls Sadr City, the ramshackle, sprawling slum in east Baghdad which is home to two-and-a-half million Shia, important cities such as Kufa and provinces such as Maysan. He can probably put 100,000 armed militiamen into the field. Much of the Baghdad police force follows him. Army barracks where Shia units are stationed have pictures of him pinned to the walls.
Once in 2004 he was wanted "dead or alive" by the US forces and dismissed as "a firebrand". They soon found that his movement had deep roots. He controls 32 out of 275 seats in the Iraqi parliament. He is the most important ally of the Prime Minister, Nouri al-Maliki. In 2004, the US and its former exile allies paid a heavy price for trying to exclude him from power. In 2005 and 2006, they recognised his strength. He became part of the political process in Iraq while opposing the US-led occupation.
Now, astonishingly the US may be about to confront Sadr and his powerful social and political movement. This could lead almost immediately to a crisis for the US and President Bush's new strategy for Iraq.
If the US Army, along with Kurdish brigades of the Iraqi army, do assault Sadr City, they are unlikely to win a clean victory. The rest of Shia Iraq is likely to explode. A confrontation will convince many Shia that the US never intends to let them rule Iraq despite their success in the elections. The US is already at war with the five million-strong Sunni community and is now fast alienating the Shia. For the first time this year, polls showed that a majority of Shia approve of armed attacks on US-led forces.
An offensive against Sadr's Mehdi Army will be portrayed as an attempt to eliminate militias. But it is, in reality, an attack on one particular militia, because it is anti-American. The Kurdish brigades in the Iraqi army take their orders from the Kurdish leaders and not from Maliki. The US also has good relations with the other Shia militia, the Badr Organisation, which is the military wing of the Supreme Council for Islamic Revolution in Iraq.
There is no doubt that the Mehdi Army includes death squads targeting Sunni - but this is also true of Badr.
Sadr first confronted the US when he twice fought the US Army in 2004. Though militarily unsuccessful the fighting established his credibility in his community. He attracted supporters because of the prestige of his family, and his blend of Iraqi nationalism and Shia religion. He is also seen as the voice of the impoverished Shia while Grand Ayatollah Ali al-Sistani and the Hawza, the Shia religious establishment, are more representative of the better-off.
His emergence as one of the most important political figures in Iraq was one of the great surprises after 2003. He is neither eloquent nor particularly charismatic, but he has made very few political mistakes. His swift rise is explained first by his family. He was born in 1974, the third son of Mohammed Sadiq al-Sadr. He is a distant cousin of Ayatollah Mohammed Baqr al-Sadr, the Shia revolutionary thinker, who was murdered by Saddam along with his sister in 1980. He had sought to develop a religious response to Marxism and Baathism by advocating a politically and socially activist Islam in contrast to the traditionally quietist Shia religious leaders.
Muqtada's father, Mohammed Sadiq al-Sadr, became influential in the 1990s. At first he was given leeway because he was an Iraqi nationalist and opposed to Iranian claims to lead the Shia of Iraq. His sermons began with the words: "No, no to America; no, no to Israel; no, no to the Devil." But it soon became clear he was also opposed to Saddam. He was assassinated by Saddam's gunmen with two of his sons in 1999.
Muqtada al-Sadr became so powerful so fast because he was in the same tradition as his relatives. His militiamen are generally not paid and supply their own weapons. They are beginning to have a core of trained, paid professionals but they were never as militarily effective as the Sunni insurgents, many of whom were experienced soldiers.
A US attack on Sadr will open another front in the war in Iraq. It would split the Shia coalition into pro- and anti-American factions. It would disrupt the Shia-Kurdish alliance. It probably would not conciliate the Sunni insurgents.
Sadr's movement thrives on martyrs. The only certain result of an all-out US assault on the Mehdi Army would be to deepen and widen the war in Iraq.
America's most wanted
Izzat Ibrahim al-Douri
Once one of Saddam's senior commanders, Douri was swiftly named leader of the Iraqi Baath party after the ex-dictator's execution. US accuses him of leading Baathist insurgents and has placed a $10m bounty on his head.
Elected member of parliament and leader of the Shia Badr Brigades, the military wing of the Iran-backed Sup-reme Council for Revolution in Iraq. Brigades accused of running death squads and have clashed with Muqtada al-Sadr's militia.
Abu Ayyub al-Masri
Also known Abu Hamza al Muhajir, Masri was identified by the Pentagon as the most likely leader of al-Qa'ida in Iraq after Abu Musab al Zarqawi's death last June. Little is known about him and some have questioned whether he even exists.
The man charged with defeating the militias
Widely regarded as the last best hope for President George Bush's quest to end sectarian violence in Iraq, Lt-Gen David Petraeus will nonetheless face the challenge of his life in confronting the Shia cleric Muqtada al-Sadr.
Lt-Gen Petraeus, 54, has been appointed by President Bush to take overall military charge of the US campaign in Iraq as soon as he receives his fourth star to become a full general and wins confirmation by the Senate. Already a veteran of two command tours in Iraq, he is also recognised as the US military's leading expert on fighting insurgencies. In 2004, he was in charge of training Iraqi soldiers.
But he was also one of the authors of an armed forces manual which appeared to cast doubt on the strategy that Mr Bush is now pursuing. "The more force used, the less effective it is... The best weapon for counter-insurgency is not to shoot," read the document, which was christened FM3-24.
Some remain sceptical that Lt-Gen Petraeus will fare any better than his predecessors. "Petraeus is being given a losing hand. I say that reluctantly. The war is unmistakably going in the wrong direction," said Barry McCaffrey, a retired army general. "The only good news in all this is that Petraeus is so incredibly intelligent and creative... I'm sure he'll say to himself, 'I'm not going to be the last soldier off the roof of the embassy in the Green Zone'."
During the initial invasion of Iraq in March 2003, Lt-Gen Petraeus was commander of the 101st Airborne Division which was critical to the taking of Baghdad. He was promoted to commander of the northern Iraq region around Mosul, where a degree of peace was restored.Reuse content