BAGHDAD -- Hard-line Shiite cleric Muqtada al-Sadr threatened "open war" as Iraqi and U.S. forces battled his Mahdi Army militia in two key strongholds yesterday, raising the specter that a truce credited with reducing violence could end soon.
The warning was the closest the cleric has come to canceling the truce he called in August, and it coincided with an Iranian denunciation of U.S. airstrikes in support of the Shiite-led government's military offensive.
The United States accuses Iran of providing training, arms and other aid to Shiite extremists. The Iranian ambassador's comments were expected to fuel the U.S. allegations and exacerbate the explosive situation.
The statement, which al-Sadr said was his "last warning," made it clear that nearly a month into the offensive against Shiite militiamen, the fighting is far from over. It also underscored the deepening rift between al-Sadr and Iraqi Prime Minister Nouri al-Maliki, exposing yet another political rivalry, this one among Shiites, that will hamper national reconciliation efforts.
If al-Sadr makes good on his threat, it would be the third time his forces have risen up against U.S. forces, and it would be a setback to Gen. David Petraeus' efforts to maintain security gains made since the deployment last year of 28,500 additional American troops.
The last of those forces is due to leave Iraq in July, and U.S. military leaders had banked on al-Sadr's truce to keep Shiite extremists pacified while soldiers focused on quelling Sunni militants linked to al-Qaida in Iraq. Recently, several large bombings characteristic of al-Qaida in Iraq have indicated that Sunni militants are regrouping in areas that had been relatively quiet in recent months.
If al-Sadr were to call his militia back to action, the United States could find itself in the same situation it was early last year, when the extreme violence prompted President Bush to send in the extra troops.
At least 12 people were reported killed yesterday in the latest battles in al-Sadr's Baghdad power base, Sadr City. In Basra, 250 miles to the south, witnesses and military officials reported fierce gun battles in Hayaniyah, a western neighborhood that had been held by the Mahdi Army.
An Iraqi police official in Basra said Iraqi forces had seized control of Hayaniyah and had detained scores of gunmen and confiscated weapons and ammunition. There was no independent confirmation of the statement.
Residents and a statement from the British military, which has about 4,100 troops stationed on the outskirts of Basra, said U.S. and British forces launched the offensive at about 6 a.m. with barrages of bombs and artillery.
Capt. Chris Ford, a British military spokesman, said the initial blasts were intended as "an impressive display of firepower" to show militia fighters what they faced if they tried to resist the Iraqi ground troops. Ford said the bombs and artillery were fired into an open field, not into residential areas.
After that, Iraqi forces began moving into Hayaniyah for the first time. Witnesses, who did not want to be identified for security reasons, reported intense fighting.
At a news conference at the Iranian Embassy in Baghdad, Hassan Kazemi Qomi, Iran's ambassador to Iraq, expressed support for Iraqi government efforts to get rid of outlaws. But, he said, U.S. strikes on Sadr City and other al-Sadr districts "will aggravate the situation and make things worse."
"The U.S. insistence on continuing this military action is a mistake, and it will lead to negative results that the Iraqi government will have to shoulder the responsibility for," Qomi said.
The U.S. has accused Iran of controlling much of the violence in Shiite districts since al-Maliki launched his offensive in Basra on March 25.
Tina Susman writes for the Los Angeles Times.