North Korean cybercriminals’ recent transfer of millions in stolen virtual currency to a Russian exchange has underlined the danger of greater cryptocurrency cooperation between the two countries, including the possibility they could use a blockchain-based financial system to evade international sanctions, experts say.

U.S.-based blockchain analysis firm Chainalysis has reported that North Korean cybercriminals transferred $21.9 million in virtual currency stolen last year from Harmony’s Horizon Bridge to an unnamed Russia-based exchange “known for processing illicit transactions.”

“This latest action marks a significant escalation in the partnership between the cyber underworlds of these