Ali was also ordered to serve an additional three years of supervised release.
Prosecutors said Ali, 60, worked for Yemen between 1997 and 2006 and shipped bulletproof vests, chemical protective suits and other equipment to the country.
Authorities also said Ali bought and shipped night-vision goggles, laptop computers and satellite phones sold to him by an undercover FBI agent posing as a U.S. Army soldier.
The Associated Press contributed to this report.