Vietnam War: The Battle of the Ia Drang begins – the first major engagement between regular American and North Vietnamese forces.

Vietnam War: The Pentagon tells U.S. President Lyndon B. Johnson that if planned operations are to succeed, the number of American troops in Vietnam has to be increased from 120,000 to 400,000.

Lyndon B. Johnson states that the United States should stay in South Vietnam until Communist aggression there is ended.

Launch of Gemini 8, the 12th manned American space flight and first space docking with the Agena Target Vehicle.

The Cuban Adjustment Act enters force, allowing 123,000 Cubans the opportunity to apply for permanent residence in the United States.

American researchers discover the Madrid Codices by Leonardo da Vinci in the National Library of Spain.

Joseph Stalin's daughter Svetlana Alliluyeva defects to the United States.

Vietnam War: off the coast of North Vietnam the USS Forrestal catches on fire in the worst U.S. naval disaster since World War II, killing 134.

Vietnam War: Operation Swift begins: U.S. Marines engage the North Vietnamese in battle in the Que Son Valley.

Vietnam War: In a propaganda ceremony in Phnom Penh, Cambodia, three American prisoners of war are released by the Viet Cong and turned over to "new left" antiwar activist Tom Hayden.

Vietnam War: American General William Westmoreland tells news reporters: "I am absolutely certain that whereas in 1965 the enemy was winning, today he is certainly losing."

Vietnam War: US and South Vietnamese forces engage Viet Cong troops in the Mekong Delta.

Viet Cong attack the United States embassy in Saigon, and other attacks, in the early morning hours, later grouped together as the Tet Offensive.

United States athletes Tommie Smith and John Carlos are kicked off the USA's team for participating in the 1968 Olympics Black Power salute.

Vietnam War: U.S. President Richard Nixon declares the Nixon Doctrine, stating that the United States now expects its Asian allies to take care of their own military defense. This is the start of the "Vietnamization" of the war.

Vietnam War: US President Richard M. Nixon makes an unscheduled visit to South Vietnam and meets with President Nguyễn Văn Thiệu and U.S. military commanders.

Vietnam War: at the apartment of French intermediary Jean Sainteny in Paris, American representative Henry Kissinger and North Vietnamese representative Xuan Thuy begin secret peace negotiations. The negotiations will eventually fail.

National Educational Television (the predecessor to the Public Broadcasting Service) in the United States debuts the children's television program ''Sesame Street''.

Cold War: Negotiators from the Soviet Union and the United States meet in Helsinki to begin SALT I negotiations aimed at limiting the number of strategic weapons on both sides.

President Richard Nixon signs the Public Health Cigarette Smoking Act into law, requiring the Surgeon General's warnings on tobacco products and banning cigarette advertisements on television and radio in the United States, starting on January 1, 1971.

Vietnam War: US President Richard Nixon announces that the United States will withdraw 40,000 more troops before Christmas

Vietnam War: The United States Military Assistance Command in Vietnam reports the lowest weekly American soldier death toll in five years (24).

Cigarette advertisements are banned on American television.

The Winter Soldier Investigation, organized by the Vietnam Veterans Against the War to publicize war crimes and atrocities by Americans and allies in Vietnam, begin in Detroit, Michigan.

Eighty-seven countries, including the US, UK, and USSR, sign the Seabed Treaty outlawing nuclear weapons in international waters.

Vietnam War: Backed by American air and artillery support, South Vietnamese troops invade Laos.

Walt Disney World opens near Orlando, Florida, United States.

Sold, dismantled and moved to the United States, London Bridge reopens in Lake Havasu City, Arizona.

Vietnam War: As part of Vietnamization, US President Richard M. Nixon sets February 1, 1972 as the deadline for the removal of another 45,000 American troops from Vietnam.

The Libertarian Party of the United States is formed.

Sound recordings are granted U.S. federal copyright protection for the first time.

Sino-American relations: The United States and People's Republic of China sign the Shanghai Communiqué.

Vietnam War: Increased American bombing in Vietnam prompts anti-war protests in Los Angeles, New York City, and San Francisco.

The United States launch ''Landsat 1'', the first Earth-resources satellite.

Vietnam War: the last United States ground combat unit departs South Vietnam.

In Reykjavík, Iceland, American Bobby Fischer beats Russian Boris Spassky and becomes the world chess champion.

The United States suffers its first loss of an international basketball game in a disputed match against the Soviet Union at Munich, Germany.

Vietnam War: In Saigon, Henry Kissinger and South Vietnamese President Nguyen Van Thieu meet to discuss a proposed cease-fire that had been worked out between Americans and North Vietnamese in Paris.

Vietnam War: White House Press Secretary Ron Ziegler tells the press that there will be no more public announcements concerning American troop withdrawals from Vietnam due to the fact that troop levels are now down to 27,000.

Vietnam War: President Richard Nixon announces that the United States will engage North Vietnam in Operation Linebacker II, a series of Christmas bombings, after peace talks collapsed with North Vietnam on the 13th.