Two ominous tweets, one written by former CIA Director John Brennan, the other by former United Nations Ambassador Samantha Power, openly threaten a sitting president — President Trump. This must be investigated. Both of these tweets raise enormous questions, not only about what is meant by these threats, but what kind of inside information these former Obama officials might be receiving from unauthorized sources. Friday night, after the long overdue firing of Andrew McCabe, the disgraced former acting FBI director, the president tweeted to the American people that McCabe’s termination (and possible loss of pension) marks a “great day for...