Between January 1961 and Nov. 22, 1963, President John F. Kennedy fundamentally changed U.S. national security policy. These changes resulted in structures and doctrines that enabled American forces to fight in Vietnam in a new way that ultimately defined Kennedy’s national security legacy.

Shortly after taking office in 1961, Secretary of Defense Robert S. McNamara began reforming the Department of Defense (DoD). At the time, the Air Force, consuming the lion’s share of DoD’s budget, was rigidly focused on the doctrine of massive retaliation adopted in 1954 by President Eisenhower’s administration. In the event of war, the Strategic Air Command’s Single Integrated Operational Plan called for the delivery of 3,200 nuclear weapons on 1,065 targets in the Soviet Union, Eastern Europe, and China. In February 1965, when McNamara asked SAC commander Gen. Thomas Power if implementing that plan would have ended human life on earth, Power responded, “If three people survive and two of them are Americans, we win.”

In 1959, U.S. Army chief of staff Gen. Maxwell Taylor retired to protest the Army’s diminished role in the military. Soon after he published, “An Uncertain Trumpet” which blasted the doctrine of massive retaliation. Attracted by Taylor’s concept of flexible response, Kennedy recalled the general to active duty first as his special advisor and then named him chairman of the Joint Chiefs of Staff. This appointment was much to the chagrin of other service chiefs, especially Air Force chief of staff, Gen. Curtis E. Lemay, who from 1948 to 1958 built SAC into the world’s premier strategic nuclear force.

Rather than massive retaliation, the Kennedy administration embraced the doctrine of flexible response. Flexible response involved fewer strategic bombers and more fighter-bombers to support a larger military capable of fighting across a spectrum of warfare: from counter-guerrilla to low-intensity conflict to conventional warfare to limited nuclear warfare. To ensure SAC maintained a qualitative nuclear advantage, flexible response included putting 1,000 solid-fueled Minuteman Missiles in underground silos and doubling the number of Polaris missile-firing submarines.

Kennedy also embraced limited warfare concepts involving special operations and covert action. He started by doubling the size of the Army’s special forces to the consternation of senior officers. While the Kennedy administration acquiesced to neutralizing communist aggression in Laos in 1962 by withdrawing U.S. military advisors supporting pro-American factions fighting the communist Pathet Lao, a covert war continued from Thailand. Through the Laotian U.S. embassy in Vientiane, the CIA ran the “secret war” in Laos. Starting in November 1961, Kennedy expanded the advisory role in South Vietnam by sending in Air Force “training” squadrons with the covert mission of providing air support for the South Vietnamese army. Kennedy’s wars of plausible deniability were on in Laos and South Vietnam.

Soon, the corrupt and inept Ngo Dinh Diem regime’s repression of Buddhists prompted riots and demonstrations. The South Vietnamese army unit’s withdrawal from the countryside to deal with the unrest invited increased aggression by the Viet Cong, increasingly supported by North Vietnam. Kennedy had, from 1961, resisted efforts to Americanize the war by sending in U.S. combat forces. Instead, he increased the presence of advisors from a few hundred in 1961 to 16,000 by November 1963. He also threatened to withdraw 1,000 advisors by the end of 1964 if the Saigon regime didn’t embrace meaningful socio-economic reforms. This leads some American scholars–determined to preserve the aura of Camelot–to posit Kennedy was on the verge of a major policy change that might have avoided the long, divisive military commitment in Vietnam. Perhaps. One might also ask what if, as some advised in 1961, Kennedy had committed 20,000 American troops to Vietnam to crush the Viet Cong while it was still weak?

While the “what ifs” of history are intriguing, it’s what actually happened that counts. In 1964, President Lyndon Johnson avoided making major decisions on Vietnam until after the November election. The focus shifted subtly, but also dramatically, to “not losing” rather than defeating the enemy and winning the war. Covert operations expanded into North Vietnam, albeit unsuccessfully, and a U.S. buildup, initially imperceptible, led to greater commitments. During 1964, the North Vietnamese stepped up infiltration of supplies and troops, rearming the Viet Cong with advanced weapons like the Kalashnikov AK-47 assault rifle. Attacks in the South coupled with North Vietnam’s reaction to U.S. covert operations in the North led to airstrikes in August 1964 and the Gulf of Tonkin Resolution. By this point, America’s involvement in Vietnam was a course initiated during the Kennedy administration.

Under the aegis of Kennedy’s “flexible response,” Eisenhower’s doctrine of massive retaliation gave way to “war management” while “not losing,” under Johnson, supplanted the pursuit of victory. Not losing is far more precarious because it depletes initiative and substitutes statistical measures of success for operational results supporting definitive strategic goals. Kennedy’s “plausible deniability,” his national security legacy, was there at the conception of America’s long Vietnam nightmare.

Dr. Earl Tilford is a military historian and fellow for the Middle East & terrorism with The Center for Vision & Values at Grove City College. He currently lives in Tuscaloosa, Alabama where he is writing a history of the University of Alabama in the 1960s. A retired Air Force intelligence officer, Dr. Tilford earned his PhD in American and European military history at George Washington University. From 1993 to 2001, he served as Director of Research at the U.S. Army’s Strategic Studies Institute. In 2001, he left Government service for a professorship at Grove City College, where he taught courses in military history, national security, and international and domestic terrorism and counter-terrorism.