Trump is known for being a counterpuncher, so on one level it’s not surprising he reacted this way to McChrystal’s withering criticism.
But when you step back, the degree to which Trump is battling America’s generals is startling, considering how he began his presidency. Trump came into office besotted by military brass, appointing retired four star Gen. James Mattis as his secretary of defense, retired four star Gen. John Kelly as his secretary of homeland security and later chief of staff, and retired three star Lt. Gen. Mike Flynn as his national security adviser. After Flynn was forced out of the White House, Lt. Gen. H.R. McMaster assumed the role of national security adviser.
Now, two years later, Trump is eager to tear down the generals. After Mattis announced his resignation with a letter distancing himself from Trump’s key foreign policy positions on December 20 and said that he would stay in the job until the end of February to allow for an orderly transition, Trump instead pushed him out at the end of December.