The U.S.'s top diplomat appeared to claim – briefly, anyway – that cryptocurrency mixing service Tornado Cash was a North Korean hacking group.

Secretary of State Antony Blinken raised eyebrows Monday when he tweeted that the U.S. Treasury Department had "sanctioned virtual currency mixer Tornado Cash, which is a U.S.-sanctioned, [Democratic People's Republic of Korea, North Korea's official name] state-sponsored hacking group, used by the DPRK to launder money."

One hour and three minutes later, the tweet had been deleted and replaced with what the Treasury Department actually alleged earlier that day: Tornado Cash was used by a North Korean hacking group to launder funds.

Blinken did not mention the deleted tweet in his subsequent one. The State Department responded to CoinDesk's request for comment with a link to the press release announcing the Tornado Cash sanctions.

READ MORE: Crypto-Mixing Service Tornado Cash Blacklisted by US Treasury

The Treasury Department's Office of Foreign Asset Control (OFAC) added Tornado Cash and more than 40 Ethereum and USDC addresses associated with the crypto mixing service to the agency's Specially Designated Nationals list Monday. OFAC claims the mixing service has been used for money laundering and other illicit purposes.

In particular, a senior Treasury official said Lazarus Group, a North Korean hacking entity, had moved hundreds of millions of dollars' worth of crypto stolen from various exchange and bridge hacks through Tornado Cash.

Ari Redbord, the head of legal and government affairs at analytics provider TRM Labs, told CoinDesk the sanctioning is "the largest, most impactful action by Treasury to date in the crypto space."

Crypto think tank Coin Center warned that Monday's action was broader than previous crypto-related sanctions designations because it targeted a decentralized protocol rather than any specific group of individuals.

At press time, Treasury Secretary Janet Yellen had not commented on her department's sanctions.