SACRAMENTO – U.S. military authorities on Wednesday began investigating whether a California National Guard unit was established to spy on U.S. citizens, as about 30 demonstrators outside guard headquarters confronted officials backed by armed soldiers. The federal probe of the nation's largest National Guard force involves the U.S. Army's inspector general, the federal National Guard Bureau's inspector general and the National Guard Bureau's legal division. The unit has raised concern among peace activists that the Guard is resorting to the same type of civilian monitoring that characterized Vietnam War-era protests. "These are your mothers, grandmothers and neighbors," said George Main,...