Bob Noel wrote:

The air defense systems in the west (WADS) and the one in Rome, NY
(NEADS) have added the capability to take in feeds from domestic radars,
including the FAA enroute radars. This all occured post-9/11.


Initially, it was the other way round. Many of the present FAA enroute
radars are former ADC radars. The FAA expanded their enroute radar coverage
in the late fifties and early sixties by acquiring feeds on USAF radar.