(WASHINGTON) -- How bad a president was Richard Nixon?
On the 40th anniversary of his resignation, a new documentary takes a fresh look at the Nixon tapes to make the case that the already vilified 37th president was not as bad as you may think -- he was worse.
"The most interesting thing that the American people aren't aware of is the kind of the dirty tricks he pulled on those good events, the things he would hold up as great achievements," said Peter Kunhardt, the director and producer of Nixon by Nixon: In His Own Words, which debuts Monday on HBO.
"When you begin hearing the behind-the-scenes maneuvering to make those great achievements happen, they were as dirty as the Watergate episode," he continued.
Ken Hughes, the author of a new book about Nixon, Chasing Shadows, joined Kunhardt for an interview with ABC News and said that one of the most shocking recent revelations about Nixon is that he intentionally prolonged the war in Vietnam for political gain.
"He realized if Saigon fell before Election Day 1972, it would take his chances of a second term down with it," Hughes said. "You can hear him discussing that in his keeping the war going, sending more Americans to fight and some to die; and it's for political reasons."
The documentary lays out which aides to Nixon were aware they were being recorded and those who were unaware. Among those who were unaware: Secretary of State Henry Kissinger.
"There is I think an extra degree of openness and candor with the people who don't know they are being taped," Hughes said. "Henry Kissinger clearly did not know he was being taped and was very angry about being taped."
Though Kissinger stayed loyal to Nixon until the end, Kunhardt said, the film demonstrates the "awkward position" that Kissinger navigated in his dealings with the "thin-skinned" president.
"He was put in this awkward position of having to be kind of a 'yes man,' and at the same time do his hugely important job at the same time," Kunhardt said.
In one recording featured in the film, Nixon can be heard asking an aide to have Kissinger's phone lines bugged after it's believed the then-secretary of state talked to a reporter without the White House's permission.
"When you watch Nixon turn on him and let his own suspicions and paranoia question Kissinger and whether they're on the same page, you feel sorry for the guy," Kunhardt said of Kissinger. "You realize that Nixon was all about what he believed in, and if you veered of course, you were kind of left to the side."
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