STORY: Who is Viktor Bout, the Russian arms dealer jailed in the United States?
The 55-year-old has been dubbed “the merchant of death” and “the sanctions buster” for his ability to get around arms embargoes.
For almost two decades, Bout became the world’s most notorious arms dealer,
selling weapons to rogue states, rebel groups and murderous warlords in Africa, Asia and South America.
His notoriety even inspired a Hollywood film starring Nicholas Cage.
Now, he's been linked to a possible swap for two U.S. citizens detained by Moscow.
Here's what we know about him.
Little is known about Bout's origins.
Biographies generally agree he was born in 1967 in Dushanbe, then the capital of Soviet Tajikistan.
A gifted linguist, he later used his reported command of English, French, Portuguese, Arabic and Persian to build his international arms empire.
A stint in the Soviet army followed,
where Bout served as a military translator including in Angola, a country that would later become central to his business.
His big breakthrough came in the days after the collapse of the Communist bloc when he cashed in on a sudden glut of discarded Soviet era weaponry.
In 2007, Douglas Farah and Stephen Braun wrote a biography entitled "Merchant of Death: Guns, Planes, and the Man Who Makes War Possible."
It reported the following details of Bout's shadowy trade.
Bout interwove his arms trafficking empire with a seemingly innocuous logistics business,
He appeared to have little in the way of firm ideology, placing business above politics.
His clients included rebel groups and militias from Congo, to Angola and Liberia.
In Afghanistan, he sold guns to Islamist Taliban insurgents and their foes in the pro-Western Northern Alliance.
The end only came in 2008, after an elaborate sting operation by the U.S. Drug Enforcement Administration in Bangkok.
There, Bout was arrested by Thai police.
After two years of diplomatic wrangling, Bout was extradited to the U.S. -- where he faced a raft of charges, including conspiracy to support terrorists, conspiracy to kill Americans, and money laundering.
In 2012, he was convicted and sentenced by a court in Manhattan to 25 years in prison.
The Russian state has been keen to get him back ever since.
Experts say the Russian state's continued interest in Bout,
plus his skills and connections in the international arms trade, hint strongly at Russian intelligence ties.
In interviews, Bout has said he attended Moscow's Military Institute of Foreign Languages, which serves as a training ground for military intelligence officers.