A federal judge on Thursday ordered federal agencies to rehire tens of thousands of probationary employees who were fired amid President Donald Trump’s turbulent effort to drastically shrink the federal bureaucracy.

U.S. District Judge William Alsup described the mass firings as a “sham” strategy by the government’s central human resources office to sidestep legal requirements for reducing the federal workforce.

Alsup, a San Francisco-based appointee of President Bill Clinton, ordered the Defense, Treasury, Energy, Interior, Agriculture and Veterans Affairs departments to “immediately” offer all fired probationary employees their jobs back. The Office of Personnel Management, the judge said, had made an “unlawful” decision to terminate them.