(CNN) -- Radical anti-American cleric Muqtada al-Sadr thanked followers who offered to launch attacks against the U.S. military in Iraq should he reinstate his notorious Mehdi Army militia, according to a posting on his website.
The exchange between a follower and al-Sadr on his website comes as Iraqi Prime Minister Nuri al-Maliki is talking with members of his government about the possibility of requesting American troops to stay in Iraq beyond a year-end deadline to withdraw.
Al-Sadr vowed earlier this year to "escalate armed resistance" if the U.S. military does not pull its troops as scheduled, a move that could destabilize the country should the Mehdi Army repeat the bloody battles it waged against American and Iraqi forces during the height of violence.
"We intended to be martyred, if you intend to lift the freeze of Imam al-Mehdi Army to defend Islam, doctrine and Iraq. Our martyrdom will be restricted only on activities against the infidel occupier without harming the civilians or any public proprieties," an unidentified follower posted on the website on Friday.
Al-Sadr responded: "Thank you dears... May God preserve you and watch over you."
A U.S. military spokesman on Sunday told CNN that, "Muqtada al-Sadr's statement speaks sufficiently for itself about his attitude toward the use of violence as an alternative to democratic processes."
"It's the same attitude that has caused so much violence for the Iraqi people in the past," Col. Barry Johnson said. "We are not inclined to characterize it further at this point."
Since 2003, al-Sadr has had the support of tens of thousands of Shiites, especially the young and impoverished in Baghdad's slums and the Shiite south.
His Mehdi Army has been considered one of Iraq's most formidable private armies following the fall of Saddam Hussein. It was blamed for some of the worst sectarian violence in Iraq before al-Sadr suspended most of its activities in 2007 and 2008, which dramatically reduced violence in Iraq.
In 2008, al-Sadr announced that most of the militia members would be transitioned into a socio-cultural organization to oppose secularism and Western thought.
A small group of hand-picked fighters called the Promised Day Brigade would continue to target the coalition, the U.S. military has said.
Al-Sadr has ratcheted his anti-American rhetoric up in recent months, raising concerns about an increase in violence as Iraq weighs whether to request that some of the 47,000 troops in Iraq stay beyond a January 1, 2012, deadline agreed upon between the two countries.
An increase in attacks in recent months against American troops has been blamed on Shiite militias, including the Promised Day Brigade. The U.S. military says the militia is using the bombings to try to take credit for driving forces out of the country.
The U.S. military maintains that the Promised Day Brigade and other Shiite militias are backed by Iran, a charge Tehran has long denied.
The cleric, who recently returned to Iraq from three years of self-imposed exile, has transformed himself from the leader of the Mehdi Army to a political player. His political bloc has now joined forces with a former rival, al-Maliki.
The al-Sadr movement emerged as one of the kingmakers in Iraqi politics last year when it won 39 parliamentary seats. The bloc's support played a major role in al-Maliki getting his second term in office.
CNN's Salma Abdelaziz contributed to this report.