MOC BAI, Vietnam--Hundreds of aging trucks and buses rumbled across the Cambodian border into Vietnam yesterday carrying thousands of soldiers in what Hanoi says is the pullout of its last 26,000 troops from Cambodia.

Led by officers riding in a U.S.-made jeep and a string of armored personnel carriers, the troops passed by thousands of schoolchildren waving flags along the sides of Highway 1.

The narrow, potholed road was one of the main routes used by Vietnamese forces when they invaded Cambodia in late 1978 and ended nearly four years of Khmer Rouge terror, installing a pro-Hanoi government.

Vietnamese schools were closed to mark the return, and relatives of soldiers ran across the border at Moc Bai.

"I am so happy to be leaving Cambodia," said a soldier from Can Tho province as his 3-year-old daughter tugged at his hair.

But many soldiers said they were worried about their future. Vietnam has said it will demobilize many after the withdrawal, and unemployment is high.

For the past decade, tens of thousands of Vietnamese troops have been in Cambodia helping the Phnom Penh government battle a coalition of guerrilla groups whose strongest faction is the Khmer Rouge.

The governments of both nations hope the troop withdrawal will convince countries around the world to end economic and diplomatic boycotts imposed after Vietnam's invasion.

Phnom Penh's Premier Hun Sen says he also hopes the pullout will persuade China and Thailand to stop aiding the three guerrilla groups.

There is widespread fear that the Khmer Rouge, which from 1975 to 1978 sent at least a million Cambodians to their death as it tried to turn the country into a primitive agrarian commune, could fight its way back to power.

"After the withdrawal of Vietnamese troops the war will continue," Hun Sen told reporters Sunday. "As to the scope of the war, we think it will depend on foreign countries," he said.

Peace talks between Cambodian factions--including Prince Norodom Sihanouk, a former leader of the country who is allied with the Khmer Rouge--and foreign powers broke down in August. Those talks were aimed at preventing bloodshed following Hanoi's removal of troops from the region.

The guerrillas have called the troop withdrawal a sham and say thousands of Vietnamese troops will remain, disguised as Cambodians.

At a series of farewell ceremonies over the past six days in key provincial towns, Cambodians cheered the departing troops and praised the communist solidarity between the two neighboring countries.

Some Cambodians said they welcomed the withdrawal, while others said they feared the Khmer Rouge, which has been on the offensive as the Vietnamese withdraw.

On Monday, Khmer Rouge radio claimed its forces had captured "a major strategic position" on the road between the key towns of Battambang and Pailin in western Cambodia.

Pailin is the center of a remote ruby mining district near Thailand, where the guerrilla groups are based.

Phnom Penh's defense minister, Gen. Tea Banh, has acknowledged the guerrillas have seized teritory near Pailin, but said the area remained under government control.

Cambodian officials have repeatedly assured reporters that they are capable of fighting the guerrillas without Vietnamese military support, but they concede that some Phnom Penh residents have begun stocking rice and other staples in anticipation of a cut-off of supplies to the capital.