Iraqi officials say two car bomb blasts targeting Sunday morning commuters in Baghdad, and clashes between security forces and militants, have killed at least 18 civilians.
The deadliest attack occurred at a busy bus station in central Baghdad. An explosives-laden car exploded outside, killing at least nine people and wounding 16 more. Thousands of people use the bus station every day or pass through the area.
In another Baghdad district, a car bomb blast killed at least four people, and shortly after sunset army artillery shells hit a Sunni village in the western suburbs, killing five more.
Also Sunday, Prime Minister Nouri al-Maliki promised there would be no military assault on Fallujah in order to spare the Anbar Province city more harm, saying Sunni Muslim tribesmen would be given more time to expel al-Qaida-linked fighters.
Mr. Maliki told Reuters his government wants "to end the presence of those militants without any bloodshed because the people of Fallujah have suffered a lot," referring to the devastating assaults by U.S. forces to evict insurgents in 2004.
In a sign of U.S. concern over the situation in Anbar, a senior United States official traveled to Iraq to meet with Mr. Maliki and other top Iraqi political leaders. Deputy Assistant Secretary for Near Eastern Affairs Brett McGurk wrapped up his trip Sunday.
In a statement, the U.S. Embassy in Baghdad said that McGurk emphasized the U.S. "provide all necessary and appropriate assistance to the government of Iraq."
Washington has ruled out sending U.S. troops back in but recently delivered dozens of Hellfire missiles to help bolster Iraqi forces. It has promised to send more missiles as well as surveillance drones.
Violence in Iraq has reached a level not seen since 2008 when the country was emerging from a period of brutal sectarian killings between the country's Sunnis and Shi'ites.
Fighters of the al-Qaida-affiliated Islamic State in Iraq and the Levant and their tribal allies took over Fallujah and parts of the nearby city of Ramadi nearly two weeks ago.
The immediate cause was Sunni anger at the Shi'ite-led government stirred by a bloody raid to arrest a Sunni politician in Ramadi. Iraqi security forces and tribesmen hostile to ISIL regained control of Ramadi, the capital of Anbar province, last week.
The Iraqi army has deployed tanks and artillery around the city of Fallujah, threatening an offensive, unless local tribesmen expel the gunmen.