The Foreign Ministry said it would seek to bring home convicted weapons dealer Viktor Bout and accused the United States of subjecting him to "controversial" detention methods.
The former Soviet Air Force officer was found guilty by a U.S. jury on Wednesday of agreeing to sell arms to people he thought were Colombian militants intent on attacking American soldiers. He faces between 25 years and life in prison in the United States.
"Our goal is to try to succeed in bringing him to his motherland," Foreign Ministry spokesman Alexander Lukashevich said Thursday in a statement, declining to say how his nation would carry this out.
"The Foreign Ministry of Russia will take and will continue to take all measures to protect the legal rights and interests of V.A. Bout, as he is a citizen of Russia," the statement said.
The Foreign Ministry said U.S. special services had subjected Bout to "unjustifiably harsh detention conditions" and "controversial methods of a physical and psychological nature that contradict existing international rights standards."
"All these factors have called into question the very facts on which the prosecution was based, and consequently the verdict," it said.
Bout had pleaded not guilty in the trial, a case that could further upset the "reset" aimed at improving U.S.-Russian relations under Presidents Barack Obama and Dmitry Medvedev.
His conviction comes weeks after Russia banned some U.S. officials from visiting the country in a tit-for-tat visa dispute over the prison death of hedge fund lawyer Sergei Magnitsky.
Bout was arrested in Bangkok in 2008 in a U.S. Drug Enforcement Administration sting operation and extradited to the United States two years later to face terrorism-related charges.
He was convicted on two counts of conspiracy to kill U.S. nationals and officers, and one count each of conspiracy to sell anti-aircraft missiles and providing material support to a terrorist organization.