B757-200
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1.8
Communication Breakdown; Confusion; Situational Awareness; Distraction
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert
Human Factors; Procedure
I was working sector 52 combined up with the north part of sector 51. The warning areas referred to as Double Shot were hot from the surface to FL500 in the western half of the airspace and in the eastern portion of the airspace the warning areas were active from the surface to FL300. It is common procedure for air carriers and GA to transition Double Shot airspace via AR4. Double Shot handed Aircraft X off to me at FL290 eastbound transiting the warning area airspace. As Aircraft X was travelling eastbound I noticed an intruder track at FL270 travelling towards Aircraft X; as the intruder target got closer to Aircraft X I noticed the target start to climb. When the intruder was at FL285; I issued a traffic alert to Aircraft X. The pilot of Aircraft X stated that they had the aircraft on TCAS but could not see the aircraft. The intruder target then descended rapidly down and stopped its altitude squawk. I immediately called Double Shot over the land line and asked if they knew who the intruder was and what it was doing. Double Shot told me that the aircraft in the warning areas were capped at FL270 and below. I told them that this was obviously wrong since Aircraft X had just been buzzed by the intruder aircraft. I was not in communication with the intruder target and had no information about who he was or what he was doing. Double Shot said they would take care of it and that was all I heard from Double Shot. Aircraft X proceeded on course without further event.Double Shot often has problems getting a hold of the fighter pilots in the warning areas. Double Shot should be able to get a hold of any and all aircraft in the warning areas at any given time and they should know exactly what each and every aircraft under their control are doing.
ZJX Controller reported another facility handed off an aircraft to him. The Controller then sees a target in the warning area climbing towards the aircraft just handed off. Controller issued traffic and called the other facility.  Other facility stated aircraft is restricted to a specific altitude. Aircraft busted altitude and buzzed the aircraft just handed off. Controller reported the violation to the other facility.