San Antonio Spurs coach Gregg Popovich has been an outspoken critic of Donald Trump since before he was elected president. Popovich recently spoke out following Trump's revoking of the Warriors' White House invitation and his comments about NFL players who kneel during the anthem, but Pop's latest outrage may be the harshest yet. Popovich, who served five years of active duty in the U.S. Air Force, was incensed by Trump's recent comments following the death of four U.S. soldiers killed in an ambush in Niger. "President Obama and other presidents, most of them didn't make calls, a lot of them didn't make calls," Trump said. "I like to call when it's appropriate, when I think I'm able to do it."