What role did the Vietnam War play in the FBI Lennon investigation?

Question: What role did the Vietnam War play in the FBI Lennon investigation?

Answer: John Lennon and his fellow Beatles had been outspoken opponents of the Vietnam War since June 30, 1966, when the group spoke out very briefly against the war, and war in general, during a Tokyo press conference. This was in direct opposition of manager Brian Epstein, who preferred that his boys shun controversy. By 1969, Epstein was dead, the Beatles were well on their way to dissolution, and John's involvement with Yoko Ono had led him to become ever more active in political dissent.

One staged event was the "Bed-In," a seriocomic stunt where the couple decided to stay in their bed at Room 1742 in Montreal, Canada's Queen Elizabeth Hotel in protest of the war. When asked by a reporter what the point of the demonstration was, Lennon responded, "We're just saying give peace a chance." Liking the phrase, Lennon decided to write a song around it, renting a tape recorder and taping an all-star singalong of the new song on May 31, 1969. It was an instant hit and became the anthem of the antiwar movement; during The Moratorium to End the War in Vietnam, a multi-city demonstration that took place on October 15, 1969, protestors sang this song. The Nixon Administration was well aware of Lennon's influence in the antiwar movement, and also aware that, in the political climate of the time, being antiwar meant being against the President.