Some are and some aren't. Fighters almost never show up. Reconnaissance aircraft, tankers, and even B-52s show up some of the time and then disappear into thin air. Cargo aircraft seem to show up most of the time. I've seen other RC-135 variants like Cobra Ball fly into and out of Kadena (Okinawa) and then disappear - I think you can presume off the Chinese coast. Over the US most trainers including T-38s show up, and there are a ton of C-130 variants in the air at any time it seems. I even saw a U-2 over CA once. British Tornados show up from time to time - looks like exercises off the British coast. Can't ever recall seeing Russian or Chinese military aircraft. I like to keep an eye on Okinawa because I liked the time I spent there - the Japanese F-15s and patrol planes flying from Naha are clearly visible on the webcams but never show up on radar. Likewise other than cargo flights, you never see fighters or most other aircraft fly in or out of Kadena (our AF Base on Okinawa).
