(CNN) – North Korea is being accused of making millions of dollars, and breaking its sanctions, by selling sand.
Analysts at the Center for Advanced Defense Studies (C4ADS), a nonprofit research organization based in Washington, D.C., said they first noticed dozens of ships mysteriously sailing to North Korea in May 2019.
The analysts said they then discovered a massive operation involving 279 ships – which had links to China – being used to dredge and transport sand.
Satellite images show clouds of sand, under what appear to be dozens of barges and dredgers, being extracted from the sea off the North Korean city of Haeju.
The alleged operation would violate United Nations sanctions passed in December 2017 banning North Korea from exporting earth and stone.
In a report released in April, U.N. investigators said North Korea made at least $22 million last year by selling sand.
North Korea has not publicly responded to the allegations, but it often refers to the sanctions as “hostile acts” and questions their legitimacy.