Aela Callan reports from Bangkok on the consequences of dropping latest charges against Bout.
A Thai court has dismissed money-laundering and fraud charges against Viktor Bout, the alleged Russian arms smuggler, removing the last legal obstacle for his extradition to the US where he is wanted on "terrorism" charges.
Bout, nick named "Merchant of Death", was to be extradited in August to face trial for conspiring to sell weapons to the Revolutionary Armed Forces of Colombia (Farc), the country's largest rebel group, after being arrested in a US-led sting operation in March 2008.
But the extradition was postponed while the extra charges brought by the US prosecutors were heard.
The Bangkok Criminal Court ruled on Tuesday to drop the money-laundering and fraud charges due to lack of evidence and other technicalities.
The extra charges were lodged by the US against Bout in February to ensure he was not set free.
The former Soviet air officer is wanted in the US on suspicion of trafficking arms to dictators and conflict zones around the world since the 1990s.
Theodore Karasik, a security analyst with the Institute for Near East and Gulf Military Affairs in Dubai, told Al Jazeera that Bout knows "plenty about Russian military arms transfers throughout the world from the 1990s up until the time of his arrest.
"Some state secrets may be leaked to the Americans and it may hurt US-Russian relations in the future. To have the future of US-Russian relations being settled in this instance in Thailand is highly unusual and does put the Thais in a bit of a tight spot."
Bout has repeatedly denied arms trafficking charges, saying that he ran a legitimate air cargo business and was in Bangkok to discuss selling planes when he was arrested.
The 43-year-old has argued that his life would be in danger if he was sent to the US because of a possible death sentence.
On Monday he said claims that he was one of the world's most prolific arms dealers were a "fantasy".
"I did nothing wrong. I am a victim of political persecution," he said after the court ruling.
Bout, who was inspiration for Nicholas Cage's character in the 2005 film Lord of War, has been held in a Thai maximum-security prison since his arrest in March 2008.
Lobbying by Moscow for his release has stirred speculation he was receiving protection from Russian authorities, who had made no apparent attempt over the years to interfere in his alleged operations.