What did Sen. John Kerry know and when did he know it about a plot to assassinate pro-Vietnam war U.S. Senators hatched at a November 1971 Kansas City meeting of the group Vietnam Veterans Against America? According to presidential biographer Douglas Brinkley, that's the question Sen. Kerry needs to answer. If it turns out that the likely Democratic presidential nominee knew of the treasonous plan, Brinkley says he had an obligation to go to the authorities. "The question is: did Kerry quit [VVAW] before Kansas City or did he quit after Kansas City," Brinkley told WABC Radio's Steve Malzberg. "If...