Back in the 70s, we were intercepted by Cuban MiG-21s a few times while transiting from CONUS to GTMO. No big deal. One time they were unusually aggressive, and a a pair of VC-10 F8E Crusaders sent them skedaddling home....
We were intercepted by Turk Phantoms while flying from Crete to Turkey. Again, just lots of waving back and forth. In this case, the Greeks never forwarded our flight plan...