Earlier this morning around 10:00am there was a USN E-6 (164387) callsign NATO 04 holding over YYZ to pick up some CF-18s callsign VIMY 11. They were using 289.400 for TAC A-A. Later joined up with CAF A-310 HUSKY 75.
Here's a link to the LiveATC archive - NATO 04 with YYZ Approach
Here's a link to the LiveATC archive - NATO 04 with YYZ Approach