Former diplomat and presidential adviser Henry Kissinger marks his 100th birthday on Saturday, outlasting many of his political contemporaries who guided the United States through one of its most tumultuous periods including the presidency of Richard Nixon and the Vietnam War.

Kissinger has had multiple heart surgeries, he's hard of hearing and blind in one eye. Even so, he told CBS News he works about 15 hours a day. 

Kissinger has been at the forefront of U.S. diplomacy for longer than most Americans have been alive. Born in Germany on May 27, 1923, Kissinger remains known for his key role in American foreign policy of the 1960s and 1970s, including eventual attempts to pull the U.S. out of Vietnam, but not before he became inextricably linked to many of the conflict's most disputed actions.

In recent years, Kissinger has continued to hold sway over Washington's power brokers as an elder statesman. He has provided advice to Republican and Democratic presidents, including the White House during the Trump administration while maintaining an international consulting business through which he delivers speeches in the German accent he has not lost since fleeing the Nazi regime with his family when he was a teenager.

Kissinger collaborated with two co-authors on a 2021 book, "The Age of AI and Our Human Future," well beyond an age at which most people are unwilling or unable to learn about the latest technology.

During eight years as a national security adviser and secretary of state, Kissinger was involved in major foreign policy events including the first example of "shuttle diplomacy" seeking Middle East peace, secret negotiations with China to defrost relations between the burgeoning superpowers and the instigation of the Paris peace talks seeking an end to the Vietnam conflict and the U.S. military's presence there.

Kissinger, along with Nixon, also bore the brunt of criticism from American allies when North Vietnamese communist forces took Saigon in 1975 as the remaining U.S. personnel fled what is now known as Ho Chi Minh City.

Kissinger additionally was accused of orchestrating the expansion of the conflict into Laos and Cambodia, enabling the rise of the genocidal Khmer Rouge regime that killed an estimated 2 million Cambodians.

Among his endorsements, Kissinger was recognized as a central driver in the period of detente, a diplomatic effort between the U.S. and the Soviet Union beginning in 1967 through 1979 to reduce Cold War tensions with trade and arms negotiations including the Strategic Arms Limitation Talks treaties.

Kissinger remained one of Nixon's most trusted advisers through his administration from 1969 to 1974, his power only growing through the Watergate affair that brought down the 37th president.

Gerald Ford, who as vice president ascended to the Oval Office following his predecessor's resignation, awarded Kissinger the Presidential Medal of Freedom in 1977, saying Kissinger "wielded America's great power with wisdom and compassion in the service of peace."

Others have accused Kissinger of more concern with power than harmony during his tenure in Washington, enacting realpolitik policies favoring American interests while assisting or emboldening repressive regimes in Pakistan, Chile and Indonesia.

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