Moqtada al-Sadr, the man Washington blames for its failure to gain control in Iraq, has rejected a call to open direct talks with the US military and has accused the Americans of plotting to assassinate him.
In an exclusive interview the Shia cleric says: "The Americans have tried to kill me in the past, but have failed... It is certain that the Americans still want me dead and are still trying to assassinate me.
"I am an Iraqi, I am a Muslim, I am free and I reject all forms of occupation. I want to help the Iraqi people. This is everything the Americans hate."
Mr Sadr, revered by millions of Iraqi Shias, spoke after leading Friday prayers in the Grand Mosque at Kufa, just over 100 miles south of Baghdad. It is one of the four Iraqi cities considered holy in Shia Islam. He always wears a black turban, the traditional symbol of a Shia cleric who can trace his ancestry to the Prophet Mohamed. But for the second time in two weeks, he also wore a white shroud -- a symbol of his willingness to be martyred, and his belief that death is close at hand.
The young cleric inherited the aura of his father, Ayatollah Mohammed al-Sadr, who was murdered by Saddam Hussein's regime. He has been a thorn in the side of the Americans since the invasion, with his Mahdi Army -- the military wing of Iraq's largest Arab grassroots political movement -- having clashed with US and British forces. The movement has been accused of kidnapping five Britons in Baghdad last week, possibly in retaliation for the death of a senior Mahdi commander in Basra at the hands of British forces, but the Sadrists deny involvement.
Mr Sadr resurfaced recently after disappearing -- possibly over the border to Iran -- when the US began its security "surge" in Baghdad early this year. He ordered his fighters in Sadr City, the Mahdi Army stronghold in the capital, not to resist the operation. Last week the US military said it wanted to open direct, peaceful talks with him, but the cleric told the IoS he rejected the idea.
"There is nothing to talk about," he said angrily. "The Americans are occupiers and thieves, and they must set a timetable to leave this country. We must know that they are leaving, and we must know when." He has reason to be wary of US offers to negotiate. As I revealed last month, respected Iraqi political figures believe the US army tried to kill or capture Mr Sadr after luring him to peace talks in Najaf in 2004.
"We are fighting the enemy that is greater in strength, but we are in the right," he said. "Even if that means our deaths, we will not stand idly by and suffer from this occupation. Islam exhorts us to die with dignity rather than live in shame."
Mr Sadr did not say how he thought the US planned to kill him. But it is clear his decision to stay out of the public eye for months was prompted by safety fears, amid a crackdown on the Mahdi Army that has seen key figures arrested and killed.
With US, British and Iraqi government forces still conducting operations against the Sadr movement and its army, the cleric warned he was prepared to launch another armed uprising. "The occupiers have tried to provoke us, but I ordered unarmed resistance for the sake of the people," he said. "We have been patient, exercising statesmanship, but if the occupation and oppression continues, we will fight." The Mahdi Army has been relatively quiet, but it is becoming more active in Baghdad, responding to a series of devastating suicide bombings by Sunni extremists.
Mr Sadr, whose rise to become one of the most influential figures in Iraq coincided with the US overthrow of Saddam, said his movement sought to follow the example of Hizbollah, the Shia armed resistance movement in Lebanon. "Hizbollah and the Mahdi Army are two sides of the same coin," he said. "We are together in the same trench against the forces of evil."
He also spoke about a spate of recent fighting between his followers and members of the Supreme Council for the Islamic Revolution in Iraq (SCIRI), the other major Shia party which has its own armed Badr faction. The clashes sparked fears that the power struggle among Shias will explode into full conflict.
"What happened with the Badr organisation and the Mahdi Army in many parts of Iraq is the result of a sad misunderstanding," he said. "We have held discussions to stop this being repeated."
Mr Sadr has always been a fervent nationalist, and has recently held talks with Sunni tribal leaders in Anbar province who have taken up arms against al-Qa'ida-affiliated extremists, while still opposing the US-led occupation. Despite his calls for cross-sectarian unity in Iraq, the Mahdi Army is widely accused of operating death squads responsible for the deaths and ethnic cleansing of thousands of Sunnis and Iraqi Christians.
Mr Sadr also insisted he opposed Iranian influence in Iraqi affairs, referring to tentative talks between the US and Iran. "We reject such interference," he said. "Iraq is a matter for the Iraqis."