Withdrawal of successive increments of U.S. ground forces, euphemistically termed re-deployments, began in August 1969, when 25,000 were brought home. Three key criteria had been established to guide the pace and magnitude of these withdrawals: improvement of South Vietnam's armed forces; enemy activity; and progress in the Paris peace negotiations. As Henry Kissinger observed in White House Years, however, the withdrawals took on a life of their own and continued at a steady rate regardless of other developments. "The last elements of flexibility were lost," Kissinger wrote, "when the Defense Department began to plan its budget on the basis of anticipated troop reductions; henceforth to interrupt withdrawals would produce a financial shortfall affecting the procurement of new weapons."
In April 1970, President Richard Nixon announced that 150,000 U.S. troops would be brought out in three increments over the coming year, and in April 1971 that an additional 100,000 would come out by the end of November of that year. By the time the Communists launched the 1972 Easter Offensive, U.S. forces were down to only 69,000 men, including just one combat brigade. Military Assistance Command, Vietnam (MACV) Commander General Creighton Abrams, an Army officer by then bereft of Army forces, fought his last battle with air and naval elements.
During these years, a superb team of top leaders was directing American affairs in Vietnam. Ambassador Ellsworth Bunker headed the country team, Abrams led the military establishment, and William Colby (who held ambassadorial rank) directed the American aspects of pacification. Stressing "one war," the harmonization of all elements of the program, these leaders were in a race to make the South Vietnamese self-sufficient before the withdrawal of U.S. forces was completed. If that eventuality had not been clear enough when the first withdrawal increment of 25,000 was announced at Midway in June 1969, it certainly became so the following month at Guam when the president enunciated what came to be known as the Nixon Doctrine. Its essence was, as its architect recalled in RN: The Memoirs of Richard Nixon, that henceforth the United States "would furnish only the materiel and the military and economic assistance to those nations willing to accept the responsibility of supplying the manpower to defend themselves."
The revised tactics specified by Abrams involved American combat units in thousands of small patrols by day and ambushes by night. Early in his tenure, Abrams also issued an order specifying that there would be no bombing or use of heavy artillery against inhabited areas without his personal approval. The Program for the Pacification and Long-Term Development of South Vietnam (PROVN) study had pointed out that it made no difference to the peasant whether destruction was caused by enemy or friendly combat actions--it was just as devastating no matter the source. "My problem is colored blue" observed Abrams, referring to how friendly forces are usually depicted on military maps, as he set about trying to curb the indiscriminate use of the massive American firepower. Abrams told his commanders, "We've got to go beyond smashing up the enemy's main-force units. We have to do that selectively, but the way to get off the treadmill is to get after his infrastructure and guerrillas."
Much of that infrastructure was in the villages, where Viet Cong functionaries collected taxes, organized carrying parties, distributed propaganda, provided guides for military units, procured food and medicine, and often imposed their will on the populace through terrorism and intimidation. Under Ambassador Colby, MACV support for pacification, including the Phoenix program that targeted the Viet Cong infrastructure, sought not only to root out this influence but simultaneously to strengthen the mechanisms of the RVN government at every level as remaining American units fought to buy time for Vietnamization and pacification to develop and prosper.
Abrams had perceived that the Communists, rather than being served by a logistical "tail" as was common in warfare, were forced to push out in front of planned operations a logistical "nose" of caches, prepared positions, and the like that were essential to their battlefield success. Finding and seizing these caches and positions became a primary objective, one that preempted many planned Communist attacks.
But the really big caches were in base areas across the border in Laos and Cambodia. In the spring of 1970, President Nixon authorized U.S. forces to do something about those sanctuaries. Launching attacks coordinated with simultaneous South Vietnamese thrusts, at the end of April American forces drove into Cambodia on a 60-day rampage that captured thousands of tons of weapons and ammunition, supplies of every description, and piles of documents. The latter included bills of lading and other proof that the Communists had indeed, as MACV had been maintaining for years but the Central Intelligence Agency (CIA) had consistently denied, been using the Cambodian port of Sihanoukville as a major route for bringing in supplies, arms, and munitions. A major benefit of the Cambodian incursion was choking off that lifeline. The operation was also assessed as having bought up to a year's additional time for Vietnamization to progress, as well as providing increased security for the dwindling American forces still in the theater.
In late January 1971, there followed another attempt to sweep enemy sanctuaries and interfere with logistical operations along the Ho Chi Minh Trail. Known as Operation LAM SON 719, this consisted of a large-scale raid by South Vietnamese forces into southern Laos. U.S. forces had by this time been prohibited by statute from engaging in ground operations in Laos or Cambodia, so they played a supporting, albeit critically important, role in the operation. American engineers upgraded Route 9 to the Laotian border near Khe Sanh, American artillery fired into Laos from positions near the border, massive American logistical support was provided to the South Vietnamese, and U.S. aviation of every description supported a multi-division thrust toward Communist base areas around Tchepone.
Again, much materiel was captured or destroyed, and the Communists took horrifying casualties in resisting the incursion, but the results were mixed. Because of congressional restrictions, South Vietnamese units had been operating for the first time without their American advisors. This proved particularly disadvantageous when it came to calling for the various kinds of assistance, from artillery to medevac to close air support. Meanwhile the Communists, relieved of any necessity to leave forces to defend the North by the perception that U.S. policy foreclosed ground intervention there, were able to concentrate virtually their entire military establishment in the path of the invading forces. An unprecedented density of anti-aircraft weaponry proved particularly effective.
The Republic of Vietnam Armed Forces (RVNAF), still inexperienced in the conduct of multi-division operations, struggled with significant problems of command and control, and when token elements reached Tchepone, the operation was terminated earlier than had been planned. Nevertheless, severe losses had been imposed on the Communists, and additional time was gained for Vietnamization to proceed. As the American pullout continued, it also became clear that LAM SON 719 was the last major action in which U.S. ground elements would take part.
One measure of the effectiveness of the cross-border operations into Cambodia and Laos was that it took the Communists until the spring of 1972 to gear up for another major offensive. When it came, however, it provided a severe test of the expanded and improved South Vietnamese armed forces, now left with only air, naval, and logistical support from the Americans. In what came to be known as the Easter Offensive, at the end of March People's Army of Vietnam (PAVN) forces struck in force at three key locationsóalong the Demilitarized Zone (DMZ), north of Saigon around An Loc, and in the Central Highlands at Kontum.
These attacks triggered major retaliatory strikes by U.S. air and naval forces, including renewed bombing of Hanoi and Hai Phong in North Vietnam for the first time since the halt ordered by Lyndon Johnson in November 1968. Large numbers of additional ships and aircraft were dispatched to the theater of war, and Hai Phong and North Vietnam's other major ports were mined, an action often urged by military leaders but never before authorized by civilian authorities.
The South Vietnamese fought well, and Abrams was pleased. American support had been important, crucially important, especially at An Loc, where B-52s literally saved the day. But Abrams made sure everybody understood that no amount of American support would have mattered had the South Vietnamese not been up to the challenge.
In late June 1972, Abrams departed Vietnam after five years of service there and headed home to be Army chief of staff. He was succeeded as Commander, U.S. Military Assistance Command, Vietnam (COMUSMACV) by General Fred Weyand, his deputy for the past two years and a man with vast experience in the war. Weyand had commanded the 25th Infantry Division in combat in Vietnam and then II Field Force at the time of the 1968 Tet Offensive. After duty as a principal on the Army Staff in the Pentagon, he went to Paris as Joint Chiefs of Staff representative on the U.S. negotiating team, and then finally returned to Vietnam. Now he had inherited the difficult and thankless task of closing down the American expeditionary force.
Apparent progress in the Paris peace talks had hit a snag in late autumn of 1972, and then-National Security Adviser Kissinger had reported virtually on the eve of the U.S. presidential election that "peace is at hand," that prospect faded away. Ever-narrowing U.S. expectations and aspirations for the war now focused on getting back American prisoners of war. On December 18, 1972, President Nixon unleashed the most concentrated bombing campaign of the war on North Vietnam. The onslaught continued until December 31, when the North Vietnamese agreed to resumption of the peace talks. Agreement was then swiftly reached, and on January 23, 1973 the document was initialed by Henry Kissinger and Le Duc Tho.
At that point, the United States was virtually out of the war. Left behind in South Vietnam were a small Defense Attache Office and the U.S. Embassy. Also left behind were the North Vietnamese forces with whom the South Vietnamese had been struggling for these many years. The peace agreement, fatally flawed, provided for a cease-fire. The Americans went home, but Communist forces remained largely where they wereóin position to fight on.
When American troop withdrawals began, commanders on the ground had expected that a substantial residual force would remain in Vietnam, one that would continue to work with the South Vietnamese much as had American forces in Korea following an earlier war. Eventually, it became clear that this was not going to be the case.
The reality was that there were set for the South Vietnamese a series of increasingly difficult hurdles: first to become capable of defeating the Viet Cong insurgency; then to defeat both the Viet Cong and the PAVN; then to do this without help from U.S. ground forces; then to do it without help from U.S. air or naval forces; and finally to do it without even American financial or logistical assistance. They accomplished all but the last, when Congress slashed financial aid to a former ally while North Vietnam's backers stayed the course.