NSA cybersecurity Rob Joyce testifies to Congress in 2021 (Al Drago/Bloomberg via Getty Images WASHINGTON — The former leader of the National Security Agency’s unit dedicated to cracking foreign computer systems warned lawmakers today that the potential mass firings of probationary federal employees would have bleak consequences for the country’s cybersecurity posture, especially when contending with malicious cyber activity from the People’s Republic of China (PRC). “I want to raise my grave