Two Chinese coastguard vessels entered Japan ’s territorial waters near the Diaoyu Islands on Tuesday, the Japanese coastguard said, a day after a Chinese naval ship chased a Russian warship away from the islets that are controlled by Tokyo but claimed by Beijing. Japan’s coastguard said Tuesday’s intrusion, the 15th this year, happened at around 4:35am, adding that its patrol vessels ordered the two Chinese ships to exit the waters immediately. Foreign Minister Yoshimasa Hayashi said Japan has made a “serious protest” with China through diplomatic channels. Calling the intrusion a violation of international law, he said at a regular press conference that Japan will deal with China’s actions “calmly and resolutely”. Japanese Defence Minister Nobuo Kishi separately said that Chinese “military activities are becoming more and more active” and Japan will “resolutely and calmly deal with any unilateral attempt to change the status quo”. The Diaoyu Islands, which Japan calls the Senkakus, remain a thorny issue in bilateral relations. Despite repeated protests from Tokyo, Beijing continues to send vessels to waters around the Japan-controlled islands. Chinese vessels have now been spotted near the islands, including in the so-called contiguous zone outside Japanese waters, for 81 days in a row, according to Japan’s coastguard. Japan drill simulated ‘foreign’ invasion of disputed East China Sea islands On Monday, a Chinese frigate chased a Russian ship away from the islets at around 7:44am, according to Japan’s defence ministry. It was the first time since June 2018 that a Chinese military vessel had entered the zone near the disputed islands, the ministry said. A Chinese warship has sailed in the zone three times before, the first in June 2016 when it did so with Russian military vessels, according to the ministry. The Russian vessel on Monday stayed near the islands for about an hour and appears to have done so to avoid a typhoon, an official from Japan’s defence ministry said. By making it appear as if it were patrolling around its own territory, China was likely trying to demonstrate its territorial claim to the islands, according to the official, who added that the move “unilaterally heightens tensions” and has created a “seriously concerning situation”. After the incident, coming amid China’s growing maritime assertiveness and increasingly robust China-Russia military ties, Tokyo lodged a protest with Beijing, Deputy Chief Cabinet Secretary Seiji Kihara said at a press conference. Japanese Senior Deputy Foreign Minister Shigeo Yamada protested to Chinese Ambassador to Japan Kong Xuanyou by phone, expressing “grave concern” over the Monday incident, Japan’s foreign ministry said. Chinese Foreign Ministry spokesman Zhao Lijian on Monday countered the initial protest, saying the islands have been “part of China’s territory”. “The activities of Chinese vessels in the adjacent waters are legitimate and lawful. The Japanese side has no right to point fingers over these activities,” he said at a press briefing. Japan also told Russia through diplomatic channels that it is closely watching recent developments around the disputed islands, as Moscow and Beijing have been increasing their naval presence around the Japanese archipelago. But Tokyo stopped short of protesting to Russia given that the country does not lay claims to the islands, and the Russian frigate entered the contiguous zone to avoid the typhoon, a ministry source said. There were no reports of Chinese or Russian frigates entering Japan’s territorial waters – which do not extend as far as contiguous waters – the ministry added. Will Russia’s Asia pivot and China’s help soften blow from sanctions? Under international law, ships of any nation, including warships, are understood to have the right to sail through the contiguous waters of a coastal nation unless they threaten the nation’s safety. Japan has over the years lodged protests to China over repeated intrusions by Chinese coastguard ships into Japanese waters around the islands. Japan has also been wary of the deepening military cooperation between China and Russia of late, such as a joint flight of bombers of the two nations over the Sea of Japan, the East China Sea and the Pacific in late May.