WASHINGTON  Accused of a 15-year run as one of the world’s biggest arms traffickers, Viktor Bout is thought to be a consummate deal maker.

Now his future may hang on whether he can strike one last bargain: trading what American officials believe is his vast insider’s knowledge of global criminal networks in exchange for not spending the rest of his life in a federal prison.

Justice Department officials were relieved on Aug. 20 when a Thai appeals court approved the extradition of Mr. Bout (pronounced boot), a Russian, from Bangkok, where he has been incarcerated since 2008. But they are wary of declaring victory in a long diplomatic wrangle with Russia until Mr. Bout actually arrives to face charges in Manhattan, a development that could be days or weeks away.

Immersed since the early 1990s in the dark side of globalization, Mr. Bout has mastered the trade and the transport that fuel drug cartels, terrorism networks and insurgent movements from Colombia to Afghanistan, according to former officials who tracked him. And he is believed to understand the murky intersection of Russian military, intelligence and organized crime.