WASHINGTON — The Marine Corps reservist arrested in Arlington National Cemetery last week with suspicious materials in his backpack was charged Thursday with firing shots last year at five military buildings in the Washington area, including the Pentagon. ...The late-night shots fired at the Pentagon, the National Museum of the Marine Corps and military recruiting offices last October and November were intended to shut down the buildings, the Justice Department said Thursday. No one was wounded in the shootings, which caused $100,000 in damage.