QAIM, Iraq - About 1,000 U.S. troops, backed by attack helicopters, swarmed into a tiny Iraqi village near the Syrian border Saturday in an offensive aimed at rooting out fighters from al-Qaida in Iraq, the country's most feared militant group, the military said.

The assault, the latest in a series of major operations this year by U.S. forces in the heartland of the Sunni-led insurgency, targeted the village of Sadah, which the military said was a base for al-Qaida militants and foreign fighters entering from Syria.

U.S. warplanes and helicopters launched strikes on targets in Sadah, sending smoke billowing into the sky, residents contacted by The Associated Press said.

The force - made up mostly of Marines, but also with soldiers and Navy sailors - rolled into the village in the morning and gunfire was heard, said a correspondent for CNN embedded with the troops. Helicopters fired on three suspicious vehicles along the way, two of which turned out to be carrying suicide bombers and the third was being loaded with weapons, CNN reported.

Sadah is a village of about 2,000 people on the banks of the Euphrates River about eight miles from the Syrian border in Iraq's western province of Anbar. The isolated community has one main road and about 200 houses scattered over a rural area.

The offensive, named Operation Iron Fist, aimed to root out al-Qaida militants who have taken hold of the village and use it as a base for attacks on Iraqi civilians and security forces, the military said in a statement.

It also aimed to stop foreign fighters from entering the country from Syria and improving security in the region before Iraq's Oct. 15 referendum on a new constitution, the military said. Sunni insurgents have vowed to derail the referendum and have launched a surge of violence that has killed at least 200 people - including 13 U.S. service members - in the past six days.