Raytheon Missile Systems engineer Wei Sun, 48, has been arrested by the FBI for taking his laptop with missile defense secrets to China and lying about it.

The Chinese-born American citizen had worked for the U.S. defense contractor for more than a decade and had earned secret-level clearance for his work with highly sensitive missile programs developed for the military. But Quartz is the first to report that prosecutors now say Sun took his company laptop on a trip overseas despite Raytheon security officials warning him not to. He also told his bosses that he only traveled to the Philippines and Singapore when he actually also traveled to China. On Jan. 7, he reportedly logged onto Raytheon’s internal network while abroad and sent a letter of resignation, saying he intended to work and study overseas. When he returned, his bosses quizzed him about inconsistencies in his itinerary, and he confessed to also having also traveled to China.

The FBI arrested him the next day and confirmed that his laptop contained secret files prohibited from export by the International Traffic in Arms Regulations as well as security software that requires a special license to take outside the states. Quartz reports that Sun is expected to change his plea to guilty as part of a plea bargain with the Department of Justice. He will appear in court Feb. 14.