Tappin read a brief statement in which he apologized for the crime.
"I regret my actions and the impact they had on my family," he said. "I am looking forward to putting this incident behind me and returning to my previous unblemished life and my wife."
As part of the plea deal, prosecutors agreed not to oppose any request by Tappin to serve part of his 33-month sentence in Britain. Along with approval from the Justice Department, Tappin also needs approval from the British government to serve time in one of its prisons.
In 2006, a Tappin associate contacted a company set up by undercover U.S. agents to buy batteries for surface-to-air missiles. U.S. authorities alleged Tappin provided undercover agents with false documents to deceive authorities and circumvent the requirement for the batteries to be licensed by the U.S. government before being exported.
Tappin must also pay an $11,357 fine, the amount he would have profited from the sale.
Tappin must report to prison by March 8. His lawyers asked that he be allowed to report to a Pennsylvania prison, something the judge said he did not oppose. Tappin will likely spend six to nine months in Allenwood before being sent back to Britain, his attorney, Dan Cogdell, said. There, he will serve no more than half of the remaining sentence, Cogdell said.