North Asia in meaning:
1. Northwest which would mean Russia
2. North - Russia, Kazakstan, Mongolia, and China
3. Northeast - Russia, China, Korea and Japan
Not sure about Russia or Kazakstan but China is OK.
I have heard Mongolia is possible with many local rarities.
Korea is technically a no, but possible by being careful.
Japan is very spotter friendly with observation deck at EVERY commercial single airport.