Democratic Senator Elizabeth Warren has asked the Commerce Department for records related to Bitmain Technologies, the Chinese manufacturer that dominates the global bitcoin mining hardware market, Bloomberg reported Friday.

In a letter sent Thursday to Commerce Secretary Howard Lutnick, Warren requested documents and communications tied to Bitmain and any actions the department has taken to address what she called "potential national security concerns," per the report. The status of a federal investigation into Bitmain remains publicly unresolved.

The probe, known as "Operation Red Sunset" and led by the Department of Homeland Security, was first reported by Bloomberg in November 2025. Investigators examined whether Bitmain's ASIC machines could be remotely manipulated for espionage or used to disrupt the U.S. power grid. The inquiry ran in parallel with National Security Council discussions that began under the Biden administration and continued into the early months of the Trump White House, according to that report.

A May 2024 federal review had already flagged "national security concerns" about Bitmain equipment deployed near a U.S. military base. A subsequent Senate Intelligence Committee report described the company's devices as presenting "several disturbing vulnerabilities" and said they could potentially be manipulated from China.

Bitmain has denied the allegations. The company told Bloomberg it "strictly complies with U.S. and applicable laws and regulations and has never engaged in activities that pose risks to U.S. national security."

Warren's letter also zeroed in on the Trump family's business ties to Bitmain. American Bitcoin, a mining company co-founded by Eric Trump and Donald Trump Jr. as a joint venture with established miner Hut 8, purchased 16,000 Bitmain rigs for $314 million in August 2025, according to SEC filings cited by Bloomberg.

Since that deal, American Bitcoin has significantly expanded its Bitmain-powered fleet. The company said earlier this month that it purchased an additional 11,298 ASICs, bringing its total owned fleet to roughly 89,242 machines representing about 28.1 EH/s of hashrate. American Bitcoin has grown its treasury to about 6,900 BTC, worth roughly $462 million at current prices.

Warren asked what steps Commerce has taken to "insulate the Commerce Department's national security decisions from the influence of firms that have business ties to the Trump family," per the report. She also wrote that "we must ensure that politically connected crypto interests do not receive special treatment and undermine our national security."

The request adds to a string of conflict-of-interest inquiries Warren has directed at the Trump administration's handling of crypto policy. In March 2025, she wrote to crypto czar David Sacks demanding financial disclosures ahead of the White House crypto summit. She has also pressed the Treasury Department over what she sees as gaps in the GENIUS stablecoin act that fail to address presidential conflicts of interest.

Democrats hold the Senate minority and cannot compel Commerce to respond. The Commerce Department did not immediately respond to a request for comment from The Block.