August 6, 2015
1. Both Japan and China are entitled to Exclusive Economic Zone (EEZ) and continental shelf up to 200 nautical miles (nm) from their respective territorial sea baseline(note: the baseline from the breadth of which the territorial sea is measured) in accordance with relevant provisions of the 1982 United Nations Convention on the Law of the Sea (UNCLOS).  As the distance between the respective territorial sea baselines of Japan and China which have opposite coasts in  the East China Sea is less than 400 nm, the maritime area where the entitlements(note: the basis of exercising legitimate rights under international law) of the two states to EEZ and continental shelf up to 200 nm overlap needs to be delimited upon their agreement.  In light of the relevant provisions of UNCLOS and international jurisprudence, boundary delimitation based on the geographical equidistance line is regarded as an equitable solution in the delimitation of such maritime area.  (Note: 1 nm = 1852 km, and 200 nm = 370.4 km)

2. (1) With regard to maritime boundary delimitation in the East China Sea, China, while refusing final delimitation on the equidistance line, argues that the unique feature of the East China Sea such as the natural prolongation of continental shelf and contrasting geographic formulation of continent and islands should be taken into consideration.  While China claims the natural prolongation of its continental shelf to the Okinawa Trough, it does not clarify the specific boundary line which it considers desirable.  

 (2) It should be pointed out that the natural prolongation theory is an idea which used to be adopted under international law in the past: it was used in the 1960s in a case of continental shelf delimitation between adjacent states, for instance.  Moreover, the relevant provisions of the 1982 UNCLOS and subsequent international jurisprudence show that there is no room to apply the natural prolongation theory to the boundary delimitation of maritime area where the distance between two opposite states is less than 400 nm.  In addition, the geographical feature of the Okinawa Trough (minor gap of sea-bed) cannot be interpreted as having any particular legal implication.  China's claim for the entitlement of continental shelf up to the Okinawa Trough is therefore baseless in light of international law today.  
3. On the basis of these considerations, Japan has taken a position that it can exercise sovereign rights and jurisdiction in accordance with international law at least on the Japanese side of the equidistance line in the maritime area pending delimitation. Based on this position, ''Act on Exclusive Economic Zone and Continental Shelf''(1996) of Japan also  defines the geographical scope of EEZ and Continental Shelf in which Japan can exercise the sovereign rights and other rights as a coastal state under international law. This does not mean at all that Japan has given up its entitlement beyond the equidistance line in any way.  Rather, it means that Japan decides to temporally limit its exercise of sovereign rights and jurisdiction to the Japanese side of the equidistance line in a period pending delimitation under international law.  Under the current circumstances where maritime boundary in the East China Sea is not yet delimited between Japan and China and China refuses Japan's argument on the equidistance line, it is important that Japan claims that it is entitled to EEZ and continental shelf up to 200 nm from its territorial sea baselines. 

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