“...maybe it was a Russian Backfire bomber...”
Are you being serious or silly?
At any rate, it wasn’t squawking anyway, was it?
I am being semi silly. I was only familiar with ATC radar. I don’t know what the capabilities of early warning radars are. I doubt if a Russian aircraft, that was trying to penetrate US airspace, would be squawking any code. I don’t even know what kind of IFF/SIF equipment Russian aircraft have, so I wouldn’t know if Russian Bears flying off the coast of Alaska are squawking anything, while out in international airspace. My job was to keep them apart, not run them together, as in running intercepts.