MOUNT OLIVE, N.C. — The U.S. military trained him in explosives and battlefield tactics. Now the Iraq War veteran and enlisted National Guard member was calling for taking up arms against police and government officials in his own country. Standing in the North Carolina woods, Chris Arthur warned about a coming civil war. Videos he posted publicly on YouTube bore titles such as “The End of America or the Next Revolutionary War.” In his telling, the U.S. was falling into chaos and there would be