China has established new airspace restrictions over a contentious area: land also claimed by Japan. These islands – Senkaku (to Japan) and Diaoyu (to China) – have been a source of tension for decades. Any non-commercial aircraft entering the zone must obey the new rules or risk facing “emergency defensive measures.” China says the new zone is about self-defense. Japan sees the move as an “escalation” and has lodged a protest. Watch this airspace.