A man who pleaded guilty to planning to place a bomb at Fort Riley, Kan., was sentenced to 30 years in prison. John T. Booker, 22, of Topeka, Kan., intended to place an explosive device containing 1,000 pounds of ammonium nitrate in a location that would have killed as many soldiers as possible, according to the Justice Department. Booker intended to die in the explosion, and video-record the event as well. “You sit in your homes and think this war is just over in Iraq. Today we will bring the Islamic State to your doorstep,” Booker said in the video. His plan went awry because the material he intended to use actually was inert, and the persons from whom he bought it in 2015 were undercover federal agents.