Three men accused of conspiring in Europe to sell military-grade weapons to informants who said they wanted to shoot down American helicopters in Colombia have pleaded not guilty.

Cristian Vintila, Massimo Romagnoli and Virgil Flaviu Georgescu appeared Thursday in a New York federal court. Their lawyers declined to comment.

Prosecutors say Vintila and Georgescu were based in Romania and Romagnoli was based in Greece. The men were extradited from Montenegro after being arrested in December.

An indictment says they offered to sell weapons ranging from pistols to rocket launchers to informants who posed as associates of the Revolutionary Armed Forces of Colombia, the decades-old rebel group known as FARC.

The indictment says the informants told the men the weapons would be used against American forces helping the Colombian government.