Richard Nixon (or as I like to call him, President Pinocchio) brought American politics to an unprecedented low (unfortunately, Tricky Dick was not the last one to do that). His escalation of the Vietnam War, his "dirty tricks" campaign to spy on protesters, his assassinations of Black Panthers and American Indian Movement activists, his overthrow of Chile's government, and Watergate, pretty much destroyed the idealistic view of "good government".
So, it's not surprising that someone would want to assassinate him. In "The Assassination of Richard Nixon", Sean Penn plays Sam Bicke, a disgruntled salesman who is going through a divorce and losing his job. After seeing Nixon's policies play out, Sam takes it upon himself to assassinate the president by crashing a plane into the White House. Maybe that conjures up memories of September 11, 2001, but Penn gives a gritty performance to the point where you can't help but completely agree with Sam's actions.