Henry Kissinger, left, and President Richard M. Nixon after Kissinger was sworn in as the 56th secretary of state in the East Room of the White House in Washington in this Sept. 22, 1973, file photo. (AP Photo, File)

As time passes, the extent to which the Vietnam War split the American public recedes from memory. We generally recognize the war's futility at this point, after years of sending young men against their will into Southeast Asia to die fighting a mostly symbolic effort to curtail the spread of global communism. But the visceral effects of the damage it did have faded. About 41,000 American troops were killed in action, with more than 58,000 dying in the conflict overall -- a fraction of those killed overall, an unknowable figure that includes combatants from North and South Vietnam and uncountable hundreds of thousands of civilians in Vietnam, Laos and Cambodia.

Young American men lived or died depending on a toss of a coin in the government's draft lottery, which determined whether or not they'd be shipped to the combat zone. So those young people, the boomer kids of the veterans of World War II, rose up in protest against the government. The counterculture was born. The political right and left staked out positions they defend today.

On the left, the embodiment of the war's evils was -- and to many still is -- Richard Nixon. He didn't start the war -- it was begun by John Kennedy and expanded by Lyndon Johnson -- but Nixon was its most enthusiastic general. He inherited a conflict that was probably unwinnable, and Nixon's national security adviser, the man who helped guide the president's strategy, was Henry Kissinger.

"I am proud to say that Henry Kissinger is not my friend," said Bernie Sanders during the PBS NewsHour democratic debate. He criticized rival Hillary Clinton for her positive comments about him, saying, "I will not take advice from Henry Kissinger." (PBS NewsHour)

It was Kissinger who in early 1969 -- about a month after Nixon took office -- orchestrated a plan to dramatically escalate airstrikes within the neutral, Vietnam-adjacent country of Cambodia, which the North Vietnamese military was using to avoid U.S. attacks (the so-called Ho Chi Minh Trail). The United States began carpet-bombing the country without informing Congress -- an early example of Nixon's long-term plan to convince the North Vietnamese that he would pull out all the stops in his effort to win the war. These attacks were hidden from official records. Planes were diverted mid-flight to fly raids into Cambodia.

When a coup replaced Cambodia's ruler with a leader amenable to the United States, we invaded on the ground. (The extent to which that coup was the work of the United States isn't clear.) When that didn't work -- and, later, as the Khmer Rouge threatened to take the nation over -- the bombings increased dramatically, including in more heavily populated areas. The United States dropped an estimated 2.7 million tons of ordnance on Cambodia; more than the 2 million tons that were dropped in all of World War II.


Bombing sites within Cambodia. (Yale University)

For which Kissinger gets the credit/blame. In one phone call with Nixon, transcribed as part of Kissinger's papers, Nixon expresses concern that heavy bombings (in this case within Vietnam) will work. Kissinger tells Nixon that a million pounds of bombs were dropped on Haiphong, a port city in the north. "Goddamn, that must have been a good strike!" Nixon replies. He continues:

Johnson's failure to subdue the North Vietnamese, in Kissinger's estimation, was that he didn't bomb enough. Kissinger and Nixon wouldn't make that same mistake. The result in Cambodia -- not the only targeted country, mind you -- may have been as many as 150,000 civilians killed. Kissinger himself figured it was about 50,000.

As national security adviser and later secretary of state, Kissinger was at the heart of a number of other controversial decisions by the Nixon administration. Among the most notable was the United States' involvement in the overthrow of Salvador Allende in Chile. Kissinger pushed Nixon to back a coup in the country, ousting the "tough, dedicated Marxist" Allende.

Nixon backed the plan, and on Sept. 11, 1973, Allende was overthrown.

His replacement was Augusto Pinochet. Pinochet tortured and murdered tens of thousands of Chileans in an attempt to maintain control of the country. In 1998, he was arrested for human rights violations, but never faced trial due to health reasons.

The coup in Chile was not the only notable event in Kissinger's life in 1973. That was also the year he received the Nobel Peace Prize.

For members of the American left, these events (and others) define Kissinger's legacy in U.S. politics. The late Christopher Hitchens, a longtime opponent of the Vietnam War, wrote a book outlining a complete prosecution of Kissinger for war crimes, which was later turned into a documentary. He's by no means alone in this belief. Just last year, the left-leaning site Salon dubbed Kissinger "The Ivy League's favorite war criminal," criticizing an appearance Kissinger made at Yale University.

Whether or not Kissinger could be prosecuted and convicted of war crimes is one thing. In the current political moment, the better question -- posed very well by Gawker's Alex Pareene -- is whether Kissinger should be embraced by the leading candidate for the Democratic presidential nomination, Hillary Clinton.

The point I’m making here is not, [Glenn Greenwald voice] HILLARY CLINTON SUPPORTS A WAR CRIMINAL. ... It’s that Hillary Clinton exists in a world where “Henry Kissinger is a war criminal” is a silly opinion held by unserious people. Her problem? Lots of those silly and unserious people want to wrest control of the Democratic Party away from its current leadership, which is exemplified by people like Hillary Clinton.

This is the core of the issue. Nixon and Kissinger are seen favorably by the American political right to this day. To the American left, they are largely reviled. In the middle, Pareene writes, sit members of the establishment like Hillary Clinton.

Bernie Sanders's indignation at Clinton's embrace of Kissinger in Thursday night's debate is the indignation of a generation of Democrats who loathed Nixon and Kissinger with every fiber of their being. This isn't a group that's inclined to back Sanders, incidentally; one of the only demographic groups Clinton won in New Hampshire was boomers. But Sanders's thoughts on Kissinger clearly don't stem from political calculations.

"I am proud to say that Henry Kissinger is not my friend," Sanders said angrily, when he raised the issue in the debate. "I will not take advice from Henry Kissinger." Clinton replied by asking Sanders from whom he would take advice. "Well, it ain't Henry Kissinger, that's for sure," he replied.

"That's fine," said Clinton. "That's fine." The audience laughed.