3 Chinese vessels raised the tension between China and Japan by entering disputed waters off Japan-controlled islands. This is the first incident in East China Sea after China informed for its air defense zone a month ago. The Chinese ships were spotted in the 12-nautical-mile territorial waters zone near one of the Senkaku islands controlled by Japan. China insists that the disputed islands have to be returned back to the country.
The 3 Chinese coast guard ships left the area without causing any problems. Japan Coast Guard informed that Chinese vessels entered the 12-nautical-mile territorial waters border for a first time.
The dispute between Japan and China is for the control over the Senkaku islands (Diaoyu Islands - Chinese) and the conflict became serious after Japan purchased 3 of 5 islands in the group from private owners (September 2012). Beijing claims that the islands have been Chinese for decades.
Air Defense Identification Zone (China)
China declared new air defense identification zone a month ago that includes an area with islands in the center of the territorial conflict with Japan. Many countries (the United States, Japan, South Korea and Australia) protested against this aggressive action. According to the new order, all aircraft have to contact China before entering the new air defense zone.
Japan’s Prime Minister Shinzo Abe has announced that no compromise will be made on the sovereignty of the islands and increased the defense budget.
The Senkaku Islands conflict
Three countries claim the territory - Japan(islands are currently under Japanese control), China and Taiwan. Senkaku islands are a group of uninhabitable islands known as Senkaku(Japan), Diaoyu(China) and Tiaoyutai(Taiwan). This disputed area was under the control of the United States for the period from 1945 to 1972 and the archipelago was controlled by Japan since 1895.
China claims that the islands were part of the country's territory in the past. Taiwan wants also to own the islands because this region is close to important shipping lanes and rich fishing grounds, and there may be hidden oil reserves.
There is a Treaty of Mutual Cooperation and Security between the United States and Japan that oblige the United States to help Japan if the islands are attacked.