Four U.S. Marines were killed in a Sunni Arab insurgent stronghold west of Baghdad as pressure mounted Sunday in parliament to replace the country's interior minister because of the security crisis in the capital.

Also Sunday, a U.S. aircraft blasted a building southwest of Baghdad used by Al Qaeda in Iraq, killing two extremists, the U.S. command announced. Four suspects were arrested.

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 over 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.

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 there.

With violence on the rise, several key Iraqi parliament members have begun pressing for replacing Interior Minister Jawad al-Bolani, who is responsible for police and paramilitary commandos who are 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 Cabinet changes, 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 that that government was preparing a "comprehensive reform plan" for both the interior and defense ministries but would not elaborate and did not mention replacing any ministers.

The Interior Ministry, which controls the police, and the Defense MNinistry, which manages the army, are the two most important and sensitive Cabinet posts.

In an attempt to mollify the two major sects, the defense post went to a Sunni while interior 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 top 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. Instead, 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 are "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."

U.S. officials did not specify where the airstrike took place, but it appeared to have been in the area around Youssifiyah which has long been a stronghold of Al Qaeda and other extremist groups.

The American statement said U.S. troops tracked a group of extremists to a house in a remote area and "coalition aircraft successfully executed the strike."

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.

In other developments Sunday:

— One policeman was killed and a civilian injured in when a bomb exploded near a police patrol in Baqouba, police said.

— In the northern city of Mosul, a suicide car bomber attacked a police patrol, injuring three policemen, police Col. Abdul Kareem Ahmed Khalaf said.