In fact, Nixon's term began 20 Jan 1969.
Since Kerry served both before and after that date, he served in Johnson's and Nixon's War, both started by one JFK (who is regal because he died so young and pretty).
History further reflects that we had involvement in Vietnam under Eisenhower. It was a matter of bipartisan policy for the era, to oppose commy expansion.
Ah, but Kerry has repeatedly and falsely stated that Nixon sent him to Viet Nam, when in fact it was Johnson who sent him to Vietnam, and it was Nixon who sent him home.