Steven Lalas, 54, was sentenced in 1993 to 14 years in prison for spying, and was placed on parole following his release from a U.S. federal prison.
Lalas is due to arrive in Greece on Sunday, to be reunited with his wife and children, the Justice Ministry said.
"Justice Minister Sotiris Hadjigakis has provided written assurances to the competent U.S. authorities, that the Greek government will fulfill any court decision regarding Mr. Lalas' parole," a statement said.
It said his parole officially expires on July 8, 2010.
Putin's official spokesman Dmitry Peskov commented on remarks in the US media about failures in launching nuclear-capable missiles in Russia
The Buk system that shot down MH17 belonged to the 53rd SAM missile brigade of the Russian Ministry of Defense, investigators say after looking at a few pictures on the net
It has long been understood that the West has been trying to subject Russian borders to total control. We have not seen such activity even during the Cold War