Nothing illegal taking place. Many times in the 70s and 80s the Bears crossed civilian airways in the MRSA at FL350-360, if they looked like getting close to a civil flight I'd call ScaTTC/LATTC and point that there was a non squawking pair xx miles in front of my fighters at the same level as their flight XX. "But who's controlling them!" The indignant reply would come. not sure, think it's Moscow Central", I'd reply.
But if you came out to the eastern Mediterranean and the Nicosia FIR you'd find U2s, RC135s, Nimrods, US 6th fleet, Israel F-15s etc all happily doing their own thing. Nearest to a collision was the U-2 that got severely bent flying through Concorde's wake.
The Israeli ATC got snidey for a while and starting telling Nicosia about the US/UK flights, so we started telling them about the IAF flights - soon stopped and an agreeable silence fell; tell Nicosia got primary radar and just about had a heart attack. Soon got used to it though and just passed traffic advisories.
Nothing new under the sun - and nothing to get shocked at the Russians about.