Artur Solomonyan, 30, and another 17 members of his international criminal group held talks for about a year with an FBI agent, who posed as a "terrorist", on the sale of Russian-made grenade launchers, machine guns and portable surface-to-air missile systems.
Solomonyan and his accomplices were arrested as soon as the Federal Bureau of Investigation collected enough evidence to charge them with conspiring to smuggle arms.
The group's arrest in 2005 was widely covered by American media. According to an FBI representative's statement at the time, Solomonyan even offered the "terrorist" enriched uranium to make an attack on the New York City Subway. However, the verdict does not mention uranium.
The sentence to another two accomplices will be made public later in March, while the other group members were sentenced earlier.