US forces said today they had killed 15 gunmen overnight in Shia areas of Baghdad.
The US military said ground forces and aircraft had been involved in several attacks. The first began yesterday evening, the military said.
Women walk past destroyed vehicles after clashes and an air strike in Sadr City today
Hundreds have died in and around Sadr City since Prime Minister Nuri al-Maliki launched a crackdown on Moqtada al-Sadr's Mahdi Army militia last month.
Sadr has demanded a withdrawal of US troops from Iraq and threatened over the weekend to wage "open war" if Mr Maliki did not call off the campaign against his fighters in Baghdad, the southern oil-hub of Basra and other Shia areas.
Since Sadr issued his threat on Saturday, the US military says it has killed around 65 militiamen in Sadr City and other Shia parts of Baghdad.