We often hear countries talking of International air-space and if another country wants to fly through it they need to gain permission.
China has extended their air space to cover the Senkaku/Diaoyu islands that are also claimed by Japan and have threatened 'emergency defensive measures' if any aircraft fly over it.
The threat is aimed at Japan and Taiwan who also claim the uninhabited islands that potentially sit amid huge deposits of oil and gas but it does lead to the obvious question, just how high does a countries air-space go?
The Aeronautical Information Manual which sets out all things aeronautical for the American flight-controllers state that anyone who flies above 50 miles (82km) vertical is an astronaut as that is where space begins.
The Fédération Aéronautique Internationale which rules over all things European flyer's has a designated mark called the Kármán line which at an altitude of 62 miles (100 km) air-space turns into space.
Not much help to the Japanese i know but probably safer to just fly around the islands for now.