Lt. Gen. Michael Flynn appears to have put the team of former special counsel Robert Mueller on the defensive, unraveling what had been suggested to be a possible unofficial deal with the prosecutors. Flynn, former national security adviser to President Donald Trump, pleaded guilty in 2017 to one count of lying to the FBI. The Mueller team recommended a light sentence for him, including no prison time, officially because of his contrition for the crime and extensive cooperation with multiple Justice Department investigations. But it appears that another, unofficial, deal may have been in place. Several weeks before Flynn signed...