My first thought was maybe it was something like an unmanned survey drone owned by an oil company or some resident's experimental aircraft. But... The Air Force chases off manned Russian aircraft with some regularity. Maybe Russia decided to go unmanned to see how far they could push into our airspace instead of flying something like a Tupolev Tu-95 like they normally do.
A Tu-95 Bear coming anywhere close to a U.S. ADIZ is very likely to get an introduction to Mr. Sidewinder or Mr. AMRAAM, considering their primary role is to deliver nuclear ordnance.
