WASHINGTON—The Army said Friday that it has taken disciplinary action against 21 officers and non-commissioned officers at Fort Hood, Texas, in connection with death last year of Spc. Vanessa Guillén, who was missing for about two months before her remains were found. The punishments, which include firing eight senior commanders, are the latest Army moves in response to Guillén’s disappearance and death, which brought to light widespread leadership failures at a base that had high rates of sexual assault, harassment, drug use and other problems. Also, in a new revelation, an Army report blamed the military for allowing Guillén’s killer to escape from custody and ultimately kill himself. It found that “poor communication” between soldiers keeping watch on Spc. Aaron Robinson failed to clearly note that he was a soldier of “heightened interest,” contributing to his ability to flee from a conference room. He committed suicide while being pursued. While …