Hmm wonder what a submarine hunting helicopter from Canada was doing there? Suppose they must have lost one of their submarines as surely they wouldn't go to someone else's waters just outside their air-space and try and hunt down, harass, annoy and gather technical data on their submarines. Surely not because that would involve them going across the world to do so in a clear act of aggression.
Surely not because among other things they would be enraged and depict the same activity from China as preparations for an imminent invasion and an unacceptable threat to their security.