Russia sentenced a worker at a weapons plant in the Urals to eight years in prison for treason on Friday.

Alexander Gniteyev, an engineer at the Avtomatika production plant in the city of Yekaterinburg, was found guilty of leaking classified information about Russia’s Bulava intercontinental ballistic missiles to foreign intelligence agencies, according to RIA Novosti.

The Moscow Times reported on Tuesday that Russia is hoping to make the Bulava the backbone of its nuclear arsenal. The 36.8-ton submarine-launched rocket can carry up to 10 nuclear warheads a distance of 5,000 miles and would have an impact 100 times greater than the bomb that struck Hiroshima, Japan in 1945.

Gniteyev is thought to be part of the team that was responsible for designing the launch and missile guidance systems. Along with the prison sentence, the Sverdlov Regional Court ordered Gniteyev to pay a 100,000 ruble ($3,200) fine.

The trial was closed to the public and the country for which Gniteyev has been accused of spying is unknown, although sources told the Russian media that he was paid $50,000 for information.

The evidence proving his guilt is sufficient, though the details of the affair are not being revealed yet because they include state secrets, a law enforcement source told the Moscow Times.

What exactly was passed and to which government is so far also not yet released.