The Military Assistance Command Vietnam’s Studies and Operations Group (MACVSOG) was the United States’ largest and most complex covert operation since World War II. More commonly referred to as SOG (Special Observation Group), the agency conducted secret operations for eight years.

Senior officials who were part of SOG included Robert McNamara, Walt Rostow, Richard Helms, William Colby, and William Westmoreland.

For over two years, SOG refused to allow agents to cross the border into Laos. It had been discussed when OP 34A was initiated, but some military advisers opposed its implementation since it violate the 1962 Geneva Accords which prohibited crossing over into Laos. But in March 1964, the JCS convinced McNamara to lift the restriction when he was told that North Vietnam had increased troop deployment through Laos and along the Ho Chi Minh trail.

In the summer of 1964, SOG was given the responsibility for carrying out reconnaissance team operations against the Ho Chi Minh trail in Laos. As NVA traffic along the Ho Chi Minh trail in Laos increased, SOG established OP 35 in the summer of 1965. It was given the authority to cross over into Laos and to conduct clandestine operations on the eastern front. North Vietnam's expansion of the trail created numerous targets for OP 35 teams to pinpoint for air strikes. Furthermore, the NVA had been operating out in the open, since nothing was done by the United States to interdict traffic. So SOG was confident that its mission into Laos would be successful.

OP 35 had headquarters in Saigon with a detachment stationed in Danang. From South Vietnam's two largest cities, SOG personnel coordinated the movement of teams into Laos. The first reconnaissance teams were located at a forward operating base in Kham Duc near the Laotian border. Five reconnaissance teams -- Iowa, Alaska, Idaho, Kansas, and Dakota -- were assigned to it in late 1965. At first, the teams could only enter Laos by foot and not by helicopter. The border between Laos and South Vietnam ran for 200 miles, but the teams had orders to cross along a portion of the border beginning 50 miles south of the DMZ. The next year, the teams were restricted even more when orders came that they could not penetrate beyond five kilometers into Laos.

As a result of the restrictions, the teams provided virtually no intelligence reports on NVA movement to SOG. Consequently, Pentagon gave the reconnaissance teams more latitude, allowing them to cross any portion of the 200 mile long border and to increase the number of their missions. OP 35 consisted of a three-phase program. First, the teams' goal was to identify NVA headquarters, base camps, and supply caches --- and then they ordered air strikes. SOG teams brought back substantial evidence of NVA activities that could not be detected by aerial photographs. Additionally, the teams captured some NVA soldiers and rescued American pilots who had been shot down.

Second, OP 35 permitted the deployment of large companies of American troops into Laos after enemy positions were identified by the reconnaissance teams. And third, OP 35 teams recruited indigenous tribesmen along the way and organized resistance groups for long range operations against the NVA. This third phase relied on White Star whose objective was to train Kha tribesmen in guerrilla warfare to fight the leftist Pathet Lao. In 1966 OP 35 carried out 111 reconnaissance missions.

OP 35 was expanded by McNamara in June 1967, and the number of missions more than doubled. But the number of Americans who died rose from three in 1966 to 42 in 1967. The Muscle Shoals project was implemented in 1967. Reconnaissance teams were sent into Laos to inject electronic sensors to monitor the movement of NVA troops in Laos. Most of the sensors were dropped by American aircraft, but some were hand-carried by reconnaissance teams and placed in strategic areas in the vicinity of the Ho Chi Minh trail. The American teams were also used to rescue personnel who were captured by the NVA or who were stranded inside Laos.

Hanoi countered in late 1966 by deploying NVA soldiers alongside the Laotian border in areas which were likely spots for American helicopters to drop off reconnaissance teams. The NVA also studied SOG's operational patterns, mapped their routes, and learned the night time conditions necessary to insert teams. Hanoi also stepped up special operations forces to attack reconnaissance teams.

OP 35's assignment was expanded in 1967 when they were ordered to insert reconnaissance teams into Cambodia to conduct intelligence missions, and to locate enemy targets and call for air strikes. The first SOG teams crossed the South Vietnam border as part of Operation Salem House, but because of constraints, their successes were rare. They were able to verify some enemy locations, infiltration routes, and supply areas.

In 1969, 454 reconnaissance teams were sent into Cambodia, the same year that Nixon began secretly bombing the "Bamboo Pentagon." Soon thereafter, Nixon announced his Vietnamization policy. In 1970, 150,000 American combat troops were withdrawn from Vietnam. The reduction of American troops had no bearing on the reconnaissance teams in Laos. However, the SOG teams assigned to Cambodia were affected by Nixon's mandate. Before Vietnamization, Operation Binh Tay provided for joint American-ARVN incursions into Cambodia to pursue Viet Cong forces who sought sanctuary after strikes in South Vietnam. But soon after Nixon's withdrawal policy went into effect, American combat forces were not allowed to enter Cambodia, and that left the poorly trained and equipped ARVN troops to operate alone.

In 1970 Salem House carried out 577 missions in Cambodia, but only 40 percent of the reconnaissance teams remained in Cambodia. Then Nixon accelerated the timetable for troop withdrawal, reducing the total number of American combat soldiers in South Vietnam to 75,000 by the end of 1971, so the impact of Salem House became negligible.

Nixon expected a major offensive by the NVA in 1972 as large numbers of Americans were sent home. His aides suspected that Hanoi's offensive would be launched from Laos. Also, 1972 was an election year.

General Creighton Abrams committed ARVN's best units to Lam Son 719. They were sent alongside the South Vietnam-Laos border just east of the DMZ with instructions to sever the Ho Chi Minh trail along Route 9. SOG argued that ARVN could not resist NVA forces, but Abrams made the decision to set up a stronghold. Abrams ordered SOG to conduct diversionary activities for the NVA just west of Khe Sanh, SOG teams dropped dummy parachutists with exploding devices. Teams also used diversionary methods to trick Hanoi into thinking that more reconnaissance groups were being inserted.

For six weeks ARVN took a brutal beating at the hands of the waiting NVA forces. Half of ARVN troops were casualties. And bad weather prevented air strikes by American pilots. The American media portrayed the Laotian incursion as a catastrophe and showed that Vietnamization was doomed to fail. Still the Nixon administration boasted of the success of Lam Son 719. From January 1971 to March 1972, OP 35 conducted useless 474 missions, 278 of which were inside the borders of South Vietnam.

By the end of 1971, SOG advised MACV that a massive NVA strike would occur. However, they could not pinpoint where the invasion would occur. On March 30, 1972 Hanoi used heavy artillery and tanks to launch a gigantic conventional invasion of the south. 120,000 NVA troops attacked across the DMZ, in the central highlands, and from Cambodia.

Beginning in January, plans were being made to terminate the entire SOG program. Finally on April 30, SOG was permanently shut down when an order from the Pacific Command directed that all its programs be transferred to South Vietnam's Strategic Technical Directorate. Over the years, OP 35 had three detachments that totaled 110 officers and 615 enlisted personnel. Each detachment had about 30 reconnaissance teams. Ninety-five percent involved operations against the Ho Chi Minh trail. SOG lost a total of 300 men on missions most of which went into North Vietnam, Laos, and Cambodia. When Hanoi released 591 American POWs in April 1973, not one SOG person was among them. Most of them presumably died in fire fights with the NVA. As many as 20 may have been captured. That became the legacy of SOG.

In well over ten years of warfare in Vietnam, the United States:

Dropped eight million tons of bombs.

Dropped 400,000 tons of napalm. Destroyed over 40 percent of Vietnam's plantations and orchards.

Sprayed 12 to 15 million gallons of Agent Orange. In 1990, an official U.S. report concluded that there was no cancer caused by Agent Orange. The tests had been conducted on Americans stationed on ships off the coast of Vietnam.

Left ten million people were homeless.

Killed three to four million people, including Cambodians and Laotians. Congress unknowingly funded CIA operations for Laos and Thailand.

In addition, 58,100 Americans were killed.

Over 400,000 Americans suffer from delayed stress syndrome.

Hundreds of thousands of Americans were injured and left crippled.

The United States dropped the equivalent of 3 H-bombs per day, enough to destroy the world 25 times over.

The top ten American defense corporations, particularly Dow Chemicals, Dupont, and International Telephone and Telegraph, grossed $11.6 billion in contracts.

Just three weeks after the termination of the Vietnam War, an incident erupted off the coast of Cambodia. The United States had just been defeated by North Vietnam, a Third World country, so now it had the opportunity to display to the world that it was still powerful and resolute. The Mayaguez, an American merchant ship, was sailing from South Vietnam to Thailand. When it neared tiny Tang Island off the coast of Cambodia, it was seized by leftists, and its crew was taken to a port on the mainland. While being held captive, Cambodian soldiers treated the Americans humanely as was testified by Captain Miller. "Even the Cambodians fed the Americans first and then ate the leftovers." They were asked a few questions, but nothing was said about spying and the CIA.

President Ford sent a communiqué via the Chinese liaison mission in Washington D.C. to the Cambodian government. Since there was no response for 36 hours, it was assumed that the Cambodian regime ignored Ford's message. At that time Ford deployed American planes strafe the Mayaguez and to land marines. In October 1976 the General Accounting Office (GAO) announced for the first time that the Chinese government did receive Ford's message. There was no response. The GAO stated that China relayed a message to the Ford administration, saying that they "expected it (the crew) released soon." Yet the American assault began 14 hours before the marine assault began. As it turned out, 41 Americans were killed, 23 in a helicopter crash, in their effort to liberate 39 crew members

More clandestine operations during the Vietnam War surfaced in February 1996. 281 Vietnamese, who were involved in covert CIA operations in the 1960s, had been assumed killed by the American government. It was revealed that they had been imprisoned by communist North Vietnam and later had been released after serving as many as 21 years. They insisted that the United States honor its pledge which was made when they became CIA operatives. According to the declassified documents, the American government cut off monthly payments to their families in the south. The total amount is $11 million. Yet the Pentagon had claimed they were dead and therefore no longer was obligated to continue payments to their families. However, the documents proved that the American government knew this was not true, that they were alive and serving sentences in North Vietnamese prison camps. No one disputed that Operation 34-Alpha existed, whereby the CIA recruited and trained South Vietnamese to infiltrate the north to spy, sabotage, and stir up local resistance. Taken north by American ships, they swam ashore, and eventually many were captured. American documents state, "Captured soon after landing" and "Captured, tried by the NVN (North Vietnamese)."