On Jan. 15, the United Nations warned that attending North Korea’s cryptocurrency conference in February will likely constitute a sanctions violation. According to Reuters, this notice was issued in a confidential report that will be submitted to the U.N. Security Council later this month.

The warning comes after a series of events sparked suspicion around North Korea’s growing interest in blockchain and cryptocurrency. In August, a panel monitoring the enforcement of U.N. sanctions reported that North Korean agents have generated about $2 billion by stealing money from financial institutions and cryptocurrency exchanges. The leaked report notes that North Korea is planning to use the money for its weapons of mass destruction programs, creating a significant cause for concern.

North Korea has been under U.N. sanctions since its first nuclear test in 2006. The country faces sanctions on trade bans of weapons-related materials and goods alongside those covering financial assets (i.e., cryptocurrency) and banking transactions.

In addition to stolen funds, the U.N.’s warning follows the indictment of Ethereum Foundation researcher Virgil Griffith, who traveled to North Korea in April last year to attend the country’s first blockchain conference.

According to the indictment, Griffith provided services to the Democratic People’s Republic of Korea without obtaining approval from the United States Treasury’s Office of Foreign Asset Control. Griffith has been charged with one count of conspiracy to violate U.S. sanctions law and faces up to 20 years in prison.