BAGHDAD, Iraq - The U.S. military defended its operations in western Iraq, insisting it is reducing insurgent attacks despite the deaths of 14 Marines in a huge bombing and four U.S. service members killed in action, the military said.

Iraq's prime minister sought to assure his demoralized public on Thursday that the government is on top of the security situation, announcing a new plan for restoring order and declaring "we are in a state of war."

U.S. military spokesman Brig. Gen. Donald Alston said American military operations in Anbar province, which includes the area where the Marines died, have succeeded in disrupting insurgent activities.

"We still have deaths. We still have suicide car bombs," he said. "But the numbers we see indicate (the insurgents) can't generate the same tempo, and I think that's because we've had some degree of effect in interdicting these forces."

Alston cited figures showing there were 13 car bombs in Iraq last week - the lowest weekly number since April. "There's a clear indication to me that the tempo has decreased."

About 1,000 U.S. Marines and Iraqi forces launched attacks in western Iraq in an operation aimed at disrupting insurgents and foreign fighters in the Euphrates River valley, the U.S. military said today.

The operation, dubbed Quick Strike, began Wednesday with Iraqi soldiers and Marines positioning their units, said a military statement. They focused on an area centered around the cities of Haditha, Haqlaniyah, and Parwana, about 130 miles northwest of Baghdad.

Today, U.S. and Iraqi troops, including Special Operations forces, moved into the city of Haqlaniyah, the Marine statement said. U.S. jets conducted an airstrike on insurgents hiding in buildings outside of the town.

Residents in the area said U.S. and Iraqi forces had cordoned off Haqlaniyah, about 140 miles northwest of Baghdad, and began conducting house to house searches. American warplanes were hovering overhead and a number of heavy explosions were heard. Witnesses said 500-pound bombs were being dropped in the area.

Alston warned that militants will likely rally their forces in a concerted effort to derail the country's political progress, including a referendum on the constitution in October and an election in December.

The president's office said a key meeting scheduled today by political leaders to hammer out differences in the draft constitution has been postponed until Sunday. The statement issued today did not say why the meeting was delayed.

The gathering was called by constitutional committee chairman Humam Hammoudi, who promised the National Assembly that the draft charter would be ready by the Aug. 15 deadline, provided the country's political leaders reach compromises on key issues including federalism, the role of Islam, and distribution of national wealth.

Prime Minister Ibrahim al-Jaafari spent today in Najaf meeting with the country's top Shiite Muslim cleric, the highly influential Grand Ayatollah Ali al-Sistani. The two were expected to talk about developments with the constitution.

U.S. leaders, who pushed hard for the committee not to seek an extension on completing the charter, considers the constitutional process vital to maintain political momentum, undermine the insurgency and pave the way for the Americans and their coalition partners to draw down troops next year.

U.S. commanders have warned that although the number of vehicle and roadside bombings are decreasing, they are increasing in potency and sophistication. Bombs on the roads or planted in vehicles account for 70 percent to 80 percent of the U.S. deaths in Iraq, command spokesman Lt. Col. Steven Boylan said.

The blast that killed the 14 Marines and their civilian translator on Wednesday was so powerful that it flipped the 25-ton vehicle and engulfed it in a huge fireball. The extremist Ansar al-Sunnah Army claimed responsibility in a Web posting and said its fighters used two bombs to destroy the vehicle.

A roadside bomb late Wednesday killed three U.S. soldiers in Baghdad, the U.S. command said. A Marine was killed Wednesday by small arms fire in Ramadi, the capital of Anbar province 70 miles west of Baghdad, the command added.

Officials in Georgia said the three soldiers killed in Baghdad were assigned to the 48th Brigade of the Georgia National Guard. The 48th has lost 11 soldiers since arriving in Iraq in May.

At least 1,826 members of the U.S. military have died since the Iraq war started in March 2003, according to an Associated Press count.

During a news conference Thursday, Prime Minister Ibrahim al-Jaafari announced a new 12-point security plan. He gave few details but said it included steps to improve intelligence, protect infrastructure and prevent foreign fighters from entering the country.

"We will not hesitate in saying this: We are in a state of war. It is one of the most dangerous types of war because it is not a conventional or a war of borders," he said.

Al-Jaafari noted that the United States and its coalition partners were trying to boost Iraqi forces to take over security from multinational forces.

"The people believe that they should depend on themselves and it is a matter of time. Iraq is now taking major steps in training its forces," he said.

Earlier in the day, Interior Minister Bayan Jabr said Iraqi security forces have started a nationwide operation to protect the country's estimated 544 voter registration centers for the constitutional referendum and election.