The weapons were handed over to the agent from Denmark’s PET security service last spring.
The US DEA requested the arrest of the men, reported to be a 34-year-old and a 40-year-old.
Law enforcement officials suspect that a Swedish citizen currently imprisoned in the United States is behind the alleged weapons deal.
Paul Mardirossian, the Swede believed to be the mastermind behind the weapons sale, is a former owner of a string of clubs in the posh Stockholm neighbourhood of Stureplan, and has been held in the United States since May after being arrested in Panama trying to sell weapons to an undercover agent.
In January, he pleaded to charges of conspiring to supply weapons to Colombian guerrillas in exchange for cocaine.
Police in Sweden arrested the two men after receiving an international arrest warrant from Denmark.
The men were arrested Tuesday morning in Malmö and Stockholm and have being held in their respective locations.
“We’ve simply helped coordinate this action; it’s a Danish matter. We’ve done our parts and are now awaiting what will happen next,” detective Lars Öjelind of the National Bureau of Investigation (NBI) told the TT news agency.