On the eve of the 100th birthday of Henry Kissinger, the mythology surrounding him continues to grow even as questions about his legacy are sure to follow him to his grave and beyond.

The United States' secretary of state and national security adviser under the presidential administrations of Richard Nixon and Gerald Ford in the 1960s and 1970s, Kissinger has not held a government post in decades, yet the long shadow of the 20th century's most famous diplomat stretches to the present day.

He continues to offer his opinions on matters such as Ukraine and artificial intelligence, because many ask him to, and perhaps out of a desire to polish his highly controversial legacy.

As he is set to join the centenarian club, Kissinger remains a notorious figure for many, whose pursuit of a pragmatic foreign policy made him indifferent to moral considerations.

Fifty years ago, on his 50th birthday, he was one of the most admired Americans, Thomas Schwartz, a US historian and professor at Vanderbilt University, has recalled.

But the author of the 2020 biography "Henry Kissinger and American Power"says history and historians have not precisely been kind to him.

Heinz Alfred Kissinger was born on May 27, 1923, in Furth, Germany, into a Jewish family that fled to New York in 1938 to avoid Nazi persecution.

Though he never lost his German accent, he assimilated quickly into American culture and attended Harvard University. Kissinger always denied his traumatic childhood had marked him for life but many pundits believe otherwise.

Jeremi Suri, author of the biography "Henry Kissinger and the American Century," said as a Jewish refugee he always feared chaos and sought to impose order on the world.

Kissinger also holds the belief that the US is a superior nation tasked with playing a special role in world affairs, Suri said.

Those who know Kissinger well say he wants to be remembered as the architect of the policy of detente with the Soviet Union that changed the course of the Cold War, and of the normalisation of relations with China, as well as the person chiefly responsible for halting nuclear proliferation and for his skills as the great Middle East mediator.

He also wishes to be remembered as a Nobel Prize-winning statesman who held secret talks with North Vietnam in the late 1960s aimed at reaching a settlement to the Vietnam War, even though as Nixon's chief adviser he also urged the president to intensify the bombing of North Vietnam and expand the conflict into Cambodia and Laos.

But he would like to erase the fact that his co-recipient of the 1973 Nobel Peace Prize, Vietnamese revolutionary general and politician Le Duc Tho, refused the award because peace had not yet been established.

Kissinger would also like to sweep some other things under the rug, namely his support for dictatorships in Argentina and Spain; his role in Operation Condor, a joint campaign of political repression and state terrorism carried out by the military regimes that controlled much of South America in the 1970s; and his support for the 1973 right-wing military coup that overthrew Chile's democratically elected socialist President Salvador Allende.

"We will not let Chile go down the drain," he was recorded as saying a few years earlier.

A best-selling 2001 book by the late British-American author and journalist Christopher Hitchens, "The Trial of Henry Kissinger," examines the former statesman's alleged war crimes in Vietnam, Cambodia, East Timor, Bangladesh, Cyprus and Chile.

Those accusations would have been unthinkable in the 1970s, when Kissinger was being portrayed as Superman on magazine covers, dated Hollywood actresses and even eclipsed his boss as a political figure.

"What would happen if Kissinger died? Richard Nixon would become president," was the running joke at the time in Washington.

In a recent interview with US broadcast network CBS, a visibly irritated Kissinger said of those grave allegations levelled by his critics that they are "a reflection of their ignorance."

Australian Associated Press