Democratic 2020 presidential hopeful Pete Buttigieg, in an interview that aired Sunday, said President Trump had slandered American troops by considering pardoning servicemen accused of war crimes -- and said the proposal threatened to undermine the country’s “legal and moral” foundations. “When you serve, you are agreeing to serve the Constitution and uphold the law and, frankly, his idea that being sent to fight makes you automatically into some kind of war criminal is a slander against veterans that could come only from somebody who never served,” the South Bend, Ind., mayor said on ABC News’ “This Week.” Buttigieg, an...