"Spy" planes
Regarding the P8 flying 'nearby', a more relevant question is "Was this the first time it was lurking near the Russian base?" since 'we' often fly as close to 'them' as we can and 'they' often fly as close to 'us' as they can, all without promoting a shooting incident (diplomatic protests are one thing, loss of life and/or hardware is a totally different ballgame).
A spyplane flying nearby much of the time is a sign of wanting to know what the other guy is up to and trying to catch him as he does something while a spyplane appearing at exactly the same time as an "anonymous" attack is either almost unbelievably stupid or propaganda...