A US man was arrested Wednesday for allegedly plotting an attack on Congress inspired by Islamic State jihadists, according to the Justice Department and the FBI. Christopher Cornell, 20, was taken into custody after he purchased two semi-automatic weapons and 600 rounds of ammunition in the US state of Ohio, according to a criminal complaint. The Justice Department said he was charged "with attempting to kill officers and employees of the United States" and possession of a firearm to carry out violent acts.