They had B52s circling over Warsaw when Russia first started this whole thing too. Just like any other military plane you see on these sites (adsbexchange.com i

They had B52s circling over Warsaw when Russia first started this whole thing too. Just like any other military plane you see on these sites (adsbexchange.com is better because it does not remove military planes and instead makes it easy to filter for them so you see only military planes) you only see them when they want to be seen. Without the transponder switched on you won't see them there. Russia could still see them on radar though. Usually only things like transporters, AWACS and the in air refuelers (Stratotankers and such) fly with transponders on. But ask yourself why there would be a Stratotanker circling all day if there were no fighter jets to refuel? Sometimes you can see a Eurofighter or some such turn on their transponders too when escorting a tanker back or during takeoff and landing.