https://www.vice.com/en_us/article/m7vdg3/us-adds-axie-infinity-hacker-to-north-korea-sanctions-list

The U.S. Treasury Department added an Ethereum address linked to the recent hack of a crypto platform affiliated with play-to-earn game Axie Infinity to the North Korean sanctions list on Thursday. 

On March 29, Sky Mavis, which operates Axie Infinity, announced that its Ronin Network "bridge" was hacked for $624 million in Ethereum and USDC tokens. The Vietnam-based company spun up the Ronin Network to make playing Axie Infinity cheaper for users, porting tokens from Ethereum to the Ronin blockchain, since the game runs on top of Ethereum where every action incurs costly "gas" fees.