All US measurements are defined by US law in the Metric system (eg an inch is exactly 2.54 centimeters by US law).

We adopted Metric in secret. That way everybody was happy. Scientists could science and convert figures easily, rednecks wouldn’t feel like they’re bowing to France, and the government could feel good for once for coming up with a solution that didn’t make anything worse.

Except for that part where at least one spacecraft violently self-destructed because half of the dev team misinterpreted metric for imperial, and the other half misinterpreted imperial for metric

Eh, these things happen. To everybody. (Although they really should have labelled their units, that’s just common sense regardless of which system you’re using!)