Advancing North Vietnamese forces this weekend sent the remnants of what was once an elite South Vietnamese army hurtling back across the Laotian border towards the protection of American units. American helicopters, jet fighters, and B-52s flew hundreds of missions in an attempt to keep the South Vietnamese units from being completely wiped out.

The U.S. command also moved two armored units towards the Laotian border, trying to prevent the North Vietnamese from sweeping across the border into South Vietnam. The units were reported to be engaged in heavy fighting. American helicopters were kept busy flying the South Vietnamese out of their surrounded remaining half-dozen bases in Laos. A correspondent for NBC news described the retreating South Vietnamese as "tired and beaten men."

Senator George McGovern (D-S.D.) said Sunday that Presidential adviser Henry Kissinger indicated in a recent private meeting that he regards the whole U.S. involvement in South Vietnam as a mistake. But McGovern, speaking on ABC's issues and Answers, added that he received no sign from Kissinger "that we are coming out very fast from Vietnam" or that there will be a complete withdrawal in the next two years.

McGovern also announced that he will introduce a bill in the Senate on Tuesday declaring the Senate in favor of recognizing the Peking government as the sole, legitimate government of China.

In North Vietnam, the U.S. also stepped up its air war over the weekend, as more than 50 American fighter-bombers struck at supply depots up to 175 miles north of the DMZ. In Pentagonese the strikes were termed "limited duration protective reaction air strikes." Hanoi reported that two U.S. jets were shot down Sunday. The U.S. command said that no planes were lost.

North Vietnamese and Pathet Lao forces stepped up the war in northern Laos, rocketing the ancient royal capital of Luang Prabang and assaulting four other nearby government positions. About 120 Americans, mostly women and children, fled Luang Prabang aboard American transport planesSunday. The city is reported to be almost completely surrounded by Pathet Lao forces.

With a kind of advance-to-the-rear logic, the South Vietnamese command announced Sunday that the Laos operation is in "its withdrawal stage" and continued to stick to their claim that the invasion has been a success. At the same time:

One North Vietnamese regiment numbering up to 2000 men defied B-52 raids that laid down nearly 100 tons of bombs and attacked a South Vietnamese marine command post only five miles from the South Vietnamese border;

A column of South Vietnamese tanks that abandoned a firebase 12 miles inside Laos was reported fleeing eastward towards the border with North Vietnamese tanks in hot pursuit;

North of Highway 9 hundreds of South Vietnamese paratroopers and rangers were moving by foot towards the border. One group of paratroopers was being led by an American helicopter gunner shot down Friday who refused rescue attempts;

Badly mauled airborne units were reported wandering around the hills north of Highway 9 waiting for U.S. helicopters to lift them out;

Several border command posts, including the headquarters of the South Vietnamese rangers, were under heavy attack. Khe Sanh, the U.S. operational base for helicopters, was shelled for the seventh straight day on Sunday.