China has a new device that may be able to track Lockheed's F-35 fighter with "passive" radar detection technology. Dubbed the DWL002, China's equipment can apparently detect stealth aircraft at distances of up to 400 kilometers -- and 600 kilometers for larger "stealth" targets -- processing "pulse, frequency agility, pulse duration, tactical air navigation system, distance measuring equipment, jitter/stagger radar, and identification friend or foe" signals emitted by the otherwise stealthy aircraft to determine its location.
To be clear, DWL002 is not an active radar system itself. As International Assessment and Strategy Center senior fellow Richard Fisher explains "Passive systems like these simply listen for any electronic emission," identifying an aircraft without having to ping it with an active radar transmitter. As such, whether or not the F-35 is itself invisible to "radar" may be a moot point.
China can "see" it anyway.
Don't look now, Lockheed Martin. But China is watching you.