From Slate:

According to local and federal officials, Thursday’s bloody assault in Chattanooga, Tennessee, was ruthless and deranged. The U.S. attorney says investigators are treating the attacks, committed by a lone gunman at a military recruiting station and a Navy and Marine Corps Reserve center, as a possible “act of terrorism.” Defense Secretary Ashton Carter calls it a “senseless act of violence.” Navy Secretary Ray Mabus says the attacks were out of bounds: “While we expect our Sailors and Marines to go into harm’s way, and they do so without hesitation, an attack at home, in our community, is insidious and unfathomable.” Senseless? Unfathomable? Terrorism? I doubt it. If this incident was inspired by Islamic jihad, as many investigators suspect, then it probably wasn’t senseless. Nor was it terrorism. It was a rational, horrific act of war.