The Department of Homeland Security is examining whether bitcoin-mining machines made by Bitmain could pose national security risks, according to a report from Bloomberg based on people familiar with an investigation led by the Department of Homeland Security. The inquiry, known as Operation Red Sunset, began in 2025 and is focused on whether the hardware could enable unauthorized remote access, espionage, or interference with the U.S. power grid.
Bloomberg reports that Operation Red Sunset has involved DHS investigators and other federal agencies. Bitmain called any assertion that it can remotely control its machines “unequivocally false” and said it complies with applicable laws. The company also said it has no knowledge of an investigation called Operation Red Sunset. A senior administration official said the government is monitoring threats of this nature but did not comment on the status of the inquiry.
The probe follows several years of rising attention from Congress and federal agencies on Chinese-owned cryptocurrency mining operations in the United States. In September 2025, Representative Zackary Nunn (R-Iowa) sent a letter to Treasury Secretary Scott Bessent urging the Committee on Foreign Investment in the United States to review Bitmain Technologies Ltd. and Cango Inc.’s U.S. operations. Nunn said the companies’ production and distribution networks could expose U.S. energy-grid connections and proprietary data to foreign influence. He warned that the firms appear to be expanding through ownership structures that may not be fully transparent to regulators or the public.
Bitmain controls an estimated 80% of the global bitcoin-mining machine market and began shifting assembly to the United States in 2024 to navigate tariff barriers. The company established a facility in Texas that assembles its Antminer series. Cango expanded in parallel after agreements with Bitmain in 2024 and 2025, becoming a top five miner by hashrate. CFIUS reviews foreign investments and transactions for national security implications, including those involving sensitive technology or infrastructure.
In July 2025, the Senate released findings on security concerns involving Chinese-owned mining facilities located near U.S. defense installations and critical infrastructure. The committee cited risks tied to proximity to military bases, including potential intelligence collection. It said Bitmain machines have had remote-control capabilities in the past, referencing a 2017 disclosure by Bitmain that code intended for anti-theft shutdown functions had remained in some devices. Bitmain said the feature was never completed and that the code’s presence was a bug. The Senate report also noted allegations of customs fraud involving imported mining machines.
Federal scrutiny has extended to U.S. ports. In November 2024, U.S.-based mining companies reported that Customs and Border Protection was holding shipments of Bitmain’s Antminer S21 and T21 models at multiple ports of entry. Companies said the Federal Communications Commission requested the holds. Several firms reported delays lasting up to two months and said they were charged daily storage fees. One company said about 200 units were being held. CBP did not give companies a reason for the holds or a timeline for release. FCC representatives later said they were unaware of any order to halt Bitmain hardware. Companies said the holds were not affecting other manufacturers.
Some firms speculated the delays could involve control boards using chips produced by Sophgo, a company under scrutiny after a chip was linked to a Huawei device. Sophgo shares a chief executive with Bitmain and supplies chips used in some Antminer models. There is no confirmed link between the import holds and that scrutiny. CBP and FCC have not commented publicly on the reason for the delays.
Federal reviews of Chinese-owned mining sites have also increased. In May 2024, the White House issued an order requiring MineOne, a cryptocurrency mining operator ultimately majority-owned by nationals of the People’s Republic of China, to divest real estate located within one mile of F.E. Warren Air Force Base in Wyoming. The order required the removal of equipment at the site. The Committee on Foreign Investment in the United States examined the property under authorities covering real estate transactions near sensitive military facilities. The Treasury Department said the proximity of the facility to a strategic missile base and the presence of specialized, foreign-sourced mining equipment presented national security risks.
During the early Trump administration, national security officials reviewed issues tied to Operation Red Sunset, per Bloomberg. Meetings involving DHS investigators and other agencies stopped in May of that year after a restructuring of the National Security Council.
