Taiwanese boats enter waters near disputed islands One of dozens of fishing boats from Taiwan that made the voyage to assert their right to fish in the disputed waters NEW: Taiwanese ships leave waters claimed by Japan after water cannons fired Japan's Coast Guard says it warned the vessels to leave its territorial waters Ten Chinese vessels in the area, Coast Guard claims Hong Kong (CNN) -- Dozens of fishing boats and 12 coast guard ships from Taiwan briefly entered waters close to a disputed island chain in the East China Sea, Japan's Coast Guard said on Tuesday. The Coast Guard said the vessels had left Japanese territorial waters by noon local time after it issued a warning and fired water cannons at the ships. It said the Taiwan coast guard vessels fired water from high-pressure hoses in return. It added that 10 Chinese surveillance ships were in the area but none had strayed into waters regarded by Japan as its territory. It said the fishing boats came as close as three nautical miles to the islands before turning away. Wang Jinn-wang, head of Taiwan's Coast Guard Administration, was quoted as saying the flotilla was "the biggest ever action" to support Taiwan's sovereignty over the islands. While Taiwan, which Beijing regards as a breakaway province, has long been a claimant in the Diaoyu/Senkaku dispute, the self-governing island has seldom rigorously advanced its claims because of an unwillingness to risk its good relationship with Japan, said Alan Dupont, a strategic analyst at the University of New South Wales in Sydney. He said Taiwan's decision to become more assertive was a response to recent action taken by China and Japan, as well as concerns over access to fishing and marine resources. Under the Law of the Sea, you have to demonstrate an ongoing interest in the islands over a period of time. It rewards countries that assert their claims," he said. Beijing and Taipei both claim they inherit China's historic sovereignty over the island. Taiwan is governed by the nationalist Kuomintang party that fled to Taiwan after losing to China's communists in 1949. "The islands get subsumed in the long-running dialogue about reunification," said Dupont. It is one situation where strategic objectives are in sync. Dupont also said Taiwan's protest would be an unwanted complication for the U.S. as it tries to strengthen its relationships in Asia to counter China's rising power. It has two of its allies involved in disputes not only with China but also with each other over the same rock.