Takeshi Ebisawa, Sompak Rukrasaranee, Somphob Singhasiri and Suksan Jullanan were arrested in New York on Monday and Tuesday on drug and arms trafficking and money laundering charges, the Justice Department said.

Under investigation by the US Drug Enforcement Administration agents in Thailand since at least 2019, the men had arranged to sell an undercover agent large quantities of heroin and methamphetamine from Myanmar's rebel United Wa State Army.

Meanwhile, Ebisawa sought to buy automatic weapons, rockets, machine guns and surface-to-air missiles for Sri Lanka's Liberation Tigers of Tamil Eelam (LTTE) -- known as the Tamil Tigers -- and the United Wa State Army, the Karen National Union and the Shan State Army, ethnic minority forces in longstanding fights with government forces.

On February 3, 2021, Ebisawa and an associate travelled to Copenhagen where the undercover DEA agent and two undercover Danish police officers showed them an array of US military arms ostensibly for sale, including machine guns and anti-tank rockets.

They also showed Ebisawa photos and a video of Stinger missiles used to target aircraft.

"We allege Mr. Ebisawa and his co-conspirators brokered deals with an undercover DEA agent to buy heavy-duty weaponry and sell large quantities of illegal drugs," the Justice Department said.

"The drugs were destined for New York streets, and the weapons shipments were meant for factions in unstable nations."

Ebisawa, the department said, was "a leader of the yakuza transnational organized crime syndicate," using an umbrella term for a number of Japanese crime families.

Jullanan has dual Thai-American citizenship while Singhasiri and Rukrasaranee are Thai citizens.

During the investigation, Ebisawa told the undercover DEA agent that Jullanan was a Thai air force general and that Rukrasaranee was a retired Thai military officer, according to the indictment.

The Justice Department did not explain how the four men came to be in the United States when they were arrested in New York.