Crypto exchanges Binance and Huobi on Tuesday froze $1.4 million in crypto tied to the Harmony Bridge heist and its alleged North Korean hackers, according to crypto tracing firm Elliptic.

In a blog post, Elliptic said it provided intelligence to the two exchanges that prompted them to freeze accounts. It said it traced the funds back to the $100 million hack of a “bridge” that allowed Harmony blockchain users to move crypto assets between different ecosystems.

Binance and Huobi did not immediately respond to a request for comment.

Federal investigators have credited North Korea’s infamous hacker wing the Lazarus Group with attacking the bridge as part of their multi-year campaign to steal hundreds of millions of crypto dollars from exchanges and infrastructure. That campaign funds North Korea’s nuclear weapons program, investigators have said.

Read more: North Korea Crypto Theft Hit Record High Last Year, UN Says: Reuters

Elliptic further claimed it followed the now-frozen Harmony funds through Tornado Cash, the privacy-focused mixing service that purports to hide one’s tracks on the public Ethereum ledger. The U.S. sanctioned Tornado Cash because of its alleged use by North Korean hackers.