A Chinese cybersecurity watchdog is accusing the U.S. government of taking part in a major cryptocurrency heist, escalating tensions around a years-long mystery involving 127,000 stolen bitcoin, now worth roughly $13 billion.

China’s National Computer Virus Emergency Response Center (CVERC) released a technical report Sunday claiming the U.S. Department of Justice seized BTC that was originally stolen in a 2020 hack targeting the LuBian mining pool.

At the time, the hacked coins were tied to Chen Zhi, chairman of Cambodia’s Prince Group, who is now under U.S. indictment for allegedly running a large-scale crypto fraud scheme.

The report lays out a timeline suggesting the hack was conducted with advanced tools, suggesting the work of a “state-level hacking organization.” That’s according to the Global Times, a Chinese state-owned newspaper affiliated with the Communist Party of China’s official newspaper, the People’s Daily.

For nearly four years, the stolen bitcoin remained untouched, and the hack largely remained unnoticed.

Then, in mid-2024, the stash was quietly transferred to new wallets. Blockchain analysis firm Arkham later tagged those wallets as belonging to the U.S. government.

CVERC’s analysis challenges the U.S. narrative that the funds were criminal proceeds. Instead, the agency claims the seizure may have been the final step in a long operation involving the same attackers behind the original theft.

The U.S. maintains the seizure was a legitimate law enforcement action.

CoinDesk has reached out to the U.S. Treasury and Department of Justice for comment but hadn't heard back by press time.