BAGHDAD, Iraq - The U.S. military launched a major combat operation today with 1,000 Marines and Iraqi soldiers in the hunt for insurgents and foreign fighters in a volatile western province straddling Syria.

Operation Spear started in the pre-dawn hours in Anbar province to hunt for insurgents and foreign fighters, the military said. The area, which straddles the Syrian border, is where U.S. forces said it killed about 40 militants in airstrikes in Karabilah on June 11.

The operation came one day after Air Force Brig. Gen. Don Alston called the Syrian border the "worst problem" in terms of stemming the influx of foreign fighters to Iraq. Syria is under intense pressure from Washington and Baghdad to tighten control of its porous 380-mile border with Iraq.

The Marines have lost 11 men and two sailors in the past week in separate incidents around Anbar.

In Baghdad, a suicide car bomber slammed into a loaded fuel tanker as it drove through Baghdad's eastern suburbs today, killing two people and injuring another six, police said. The car hit the tanker after it missed an Iraqi army patrol in the Kamaliyah suburb.

Elsewhere, a suicide car bomber rammed into an Iraqi army convoy in northern Iraq early this morning, injuring at least seven people - three soldiers, three civilians and one policeman, police Brig. Gen. Sarhat Qadir said. The blast came on the heels of a suicide car bomb on Baghdad's airport road Thursday that killed at least eight police officers and wounded 25 more.

On June 11, the Marines had engaged the insurgents after the militants took control of a road just outside Karabilah near the Iraqi-Syrian frontier city of Qaim, about 200 miles west of Baghdad.

The battle was also where insurgents had killed 21 people, beheading three of them. Those bodies, found June 10, were believed to belong to a group of missing Iraqi soldiers.

On Thursday, Alston blamed Iraq's recent spike in bloodshed on Jordanian-born terrorist leader Abu-Musab al-Zarqawi, who purportedly condoned the killing of fellow Muslims and denounced the country's majority Shiites as collaborators with the Americans.

Alston took aim at al-Zarqawi, saying the leader of al-Qaida in Iraq is most responsible for the nearly 1,100 violent deaths since the Shiite-led government took office seven weeks ago.

Alston's focus on al-Zarqawi, whose small group is blamed for many of the bloodiest attacks and hostage-takings in Iraq, apparently was aimed at reinforcing growing dissatisfaction among Iraqis over insurgents targeting civilians. He said that anger has brought an increase in calls to tip lines.

He said tips to Iraqi authorities resulted in Tuesday's arrest of Mohammed Khalaf, also known as Abu Talha, who was al-Qaida's leader in Mosul, 225 miles northwest of Baghdad.