Christopher Tappin, 66, pleaded guilty in November to attempting to ship specialized batteries used for the Hawk air defense missile to Iran using false export papers.
"Those who violate federal law for monetary gain, and in the process put the national security of the United States and its allies at risk, will face prosecution and punishment for their callous disregard for the public's safety," United States Attorney Robert Pitman said in a statement.
Tappin was caught in a sting operation involving an undercover federal agent.
He admitted to wiring about $25,000 from a London bank to pay for five batteries and even paid the agent $5,000 for fines after they were supposedly seized by customs officials.
He planned to ship them to Iran through Britain.
His co-conspirators -- Cyprus-based Robert Gibson and Portland, Oregon, resident Robert Caldwell -- were sentenced to 24 months and 20 months, respectively, in federal prison in 2007.
Tappin will also have to pay a fine of $11,357.14: his anticipated profit from the scheme.