Chinese Bitcoin Gear Has Been Focus of National Security Probe

A Chinese manufacturer that sells most of the world’s Bitcoin-mining machines — including 16,000 of them to a venture backed by two of President Donald Trump’s sons — has been the focus of a months-long federal investigation to assess whether its products pose risks to US national security.

The use of Beijing-based Bitmain Technologies Ltd.’s machines at a site near a military base raised “significant national security concerns” in a federal review last year. And the firm’s name surfaced again in July in a report from the Senate Intelligence Committee that said its devices could be manipulated from China and that ...