If you are monitoring from Europe, 8992 is a secondary frequency for the French Air Force.
https://priyom.org/military-stations/france/air-force#circusI do not have any insight as to any formal arrangement that might exist, but the FAF seems to have a near-monopoly on 8992 during the HFGCS' typical off hours (night-time for CONUS time zones), and gave me the impression of necessarily "working around" US military broadcasts that might take place anyways, rather than treating them as a nuisance.