Also Sunday, a U.S. F-16 jet dropped two precision-guided bombs on a building near Baghdad used by militants affiliated with a group believed responsible a mortar-and-rocket attack in Baghdad's mostly Shiite district of Karradah last week that killed at least 31 people, U.S. officials said.
Two militants and a child were killed in the airstrike, and four suspects were arrested, the United States said. American officials expressed regret about the child's death and said "terrorists continue to deliberately place innocent Iraqi women and children in danger by their actions and presence."
"We do everything possible to avoid civilian casualties during these operations," U.S. spokesman Lt. Col. Barry Johnson said. "We deeply regret the loss of an innocent life while eliminating a group responsible for targeting so many other innocent Iraqis.
"We believe that countless more Iraqis would have been at risk had we not taken immediate action to eliminate this terrorist cell when we discovered their exact location."
U.S. officials did not specify where the airstrike took place, but it appeared to have been in the area around Youssifiyah that has long been a stronghold of al Qaeda and other extremist groups.
The Marines, from Regimental Combat Team 7, died Saturday in Anbar province, the heavily Sunni Arab region west of Baghdad that includes such flashpoints as Ramadi and Haditha, a U.S. statement said without further details.
So far this month, 44 U.S. service members have died in Iraq — including 10 in Anbar province during the past week. That underscores the threat to U.S. troops from Sunni insurgents, despite the attention paid to recent sectarian violence between Sunni and Shiite Muslims in Baghdad.
In other developments:
The U.S. command confirmed Saturday it is sending about 3,700 troops from elsewhere in Iraq to Baghdad to try to quell violence in the capital. The 172nd Stryker Brigade, which had been due to leave Iraq after a year's assignment, will be sent from the north to the capital, Gen. George W. Casey Jr., the top U.S. commander in Iraq, said. "Baghdad is a problem for us, there's no doubt about that. We are fighting Iraqis who are killing Iraqis," said Lt. Gen. Peter Chiarelli, commander, multi-national corps, told CBS News correspondent Mark Strassmann.
The U.S. command is moving 3,700 troops from Mosul to Baghdad to cope with the crisis in the capital, raising concern that violence could flare up again in that northern city as American forces scale back.
With violence on the rise, several key Iraqi parliament members are pressing to replace Interior Minister Jawad al-Bolani, who is responsible for police and paramilitary commandos at the forefront of the fight against extremists in the capital.
"Some changes will take place in Cabinet during the coming days," said Hassan al-Suneid, a member of Prime Minister Nouri al-Maliki's Dawa party. "There is talk among the Cabinet, the (Shiite) alliance and parliament about changing the interior minister because he is unqualified."
Bassem Sharif, a lawmaker from the Shiite party Fadhila, confirmed there were moves underway to demand changes in the Cabinet, including the Interior Ministry.
"The structure of the Interior Ministry is not right — unmarked cars, no checkpoints formed yet ... So far they have done nothing," Sharif said. "There are only excuses."
Al-Bolani, a Shiite, was chosen for the sensitive post after protracted negotiations among the various religious and ethnic parties within the national unity government. The interior and defense posts were not filled until June 8 — nearly three weeks after the rest of the Cabinet.
Al-Maliki told reporters the government was preparing a "comprehensive reform plan" for both the interior and defense ministries, but he did not mention replacing any ministers.
The Interior Ministry, which controls the police, and the Defense Ministry, which manages the army, are the two most important and sensitive Cabinet posts.
In an attempt to mollify the two major sects, the Defense Ministry post went to a Sunni while the Interior Ministry was given to a Shiite. But the Americans demanded the jobs go to people without ties to avowedly sectarian parties — a tall order in a country where politics is organized along sectarian and ethnic lines.
The U.S. demand was aimed at pacifying Sunni Arabs, who accused the Interior Ministry of widespread abuses against civilians when the post was held by Bayan Jabr, a key member of the biggest Shiite party.
After the parties failed to agree on a choice, al-Bolani, 46, got the job despite no background in security or high-level administration. He was an engineer with the Iraqi air force until 1999.
In a speech to parliament, the embattled minister acknowledged that "disloyal and corrupt elements" had infiltrated the police and government and were "not performing their duties in a proper manner."
"We will not allow any act of violence and sectarianism inside the ministry," he told parliament. "Our country faces a big confrontation and challenges. We will fight kidnapping, terrorism and killing. We will dismiss those who do not respect the law."
As part of a crackdown on corruption, the United States said Iraqi forces arrested an Iraqi police colonel in Wasit province, southeast of Baghdad, on Sunday because of his alleged involvement "in numerous illegal and insurgent activities."
Also Sunday, al-Maliki warned television stations against broadcasting footage that could undermine stability and fan sectarian hatred. A statement by the prime minister's office cited news reports that "capitalize on the footage of victims of terrorist attacks."
The prime minister called on media outlets to "respect the dignity of human beings and not to fall in the trap set up by terrorist groups, who want to petrify the Iraqi people."
There has been an increase in biased reporting by Shiite and Sunni television stations that focus on the suffering of their communities — often with little mention of the other.