What’s with the CF-18 flyovers?

Earlier this afternoon I saw a single CF-18 fly over Villeray, and just now a pair of them cut across the sky also on a roughly southwestern heading. No, I don’t keep a sky watch, and Villeray’s under a flight path anyway, but you can’t mistake the scream of those engines for the rumble of a passenger jet.

Anyone know why these planes have been spotted over Montreal this summer? (There were more reports earlier on, and today was the first time I’ve seen any in awhile.)