The JFK drone “hovering” in the landing approach was NOT detected by JFK civilian, military, or DHS radar by all accounts to date, nor has the FBI publicly identified the perpetrator of the near-miss.
The FAA issues “no-fly” advance warning announcements called NOTAMS to law-abiding citizens for all aircraft including model aircraft and drones when VIPS will be in an area. But terrorists will not observe these and there isn’t much evidence of detection ability by authorities for violations by mini-drone operators that I have seen.
The FBI asked the public near JFK to be vigilant and to report any past or future suspicious drone activity to them.