Late last September, Kyodo News, a Japanese news agency, reported that the Japanese government had privately informed the Chinese government that the captain (commander) of the Japan Maritime Self-Defense Force destroyer JS Suzutsuki (standard displacement 5,050 tons, length 151 meters) had mistakenly entered Chinese territorial waters in July 2024, unaware of his vessel’s exact location. In the early hours of July 4, the Suzutsuki traversed Chinese territorial waters for approximately 20 minutes, within 12 nautical miles (about 22 kilometers) of the coast of Zhejiang, China. The Japan Maritime Self-Defense Force effectively dismissed the captain, citing the incident as a serious error. This marked the first time since the establishment of the Self-Defense Forces in 1954 that a Maritime Self-Defense Force destroyer had entered Chinese territorial waters without prior notification to the Chinese government.
However, the captain’s blunder was a failure in basic seamanship, namely accurately determining his ship’s position. It was not the vessel deliberately entering Chinese territorial waters without first notifying the Chinese government.
International law allows for the right of innocent passage in territorial waters by foreign ships (Article 17 of the United Nations Convention on the Law of the Sea, or UNCLOS), and the coastal country is obligated not to hamper the right of innocent passage of foreign ships (Article 24 of UNCLOS). The right of innocent passage refers to the right of a foreign ship to enter and pass through the territorial waters of a coastal country without prior approval, on the condition that it does not infringe upon the interests of the coastal country. There has been a long-standing debate over whether the right of innocent passage through territorial waters applies not only to commercial vessels but also to warships. A clear resolution to this debate has not been established, even under UNCLOS, which was adopted in 1982 and entered into force in 1996.
Each country addresses this issue differently. Some, like Japan and Russia, allow the innocent passage of foreign warships through their territorial waters, while others require prior permission (such as China and Vietnam) or prior notification (e.g., South Korea and India).
Japan takes the position that foreign warships and government ships possess the right of innocent passage through its territorial waters, based on its understanding of UNCLOS. However, Japan views China Coast Guard (CCG) vessels entering Japan’s territorial waters around the Senkaku Islands (claimed by China as the Diaoyu Islands) as “non-innocent” under Article 19, paragraph 2 (l) of UNCLOS, on the grounds that the CCG is conducting law-enforcement activities under Chinese domestic law, and thus exercises its right of protection under Article 25, paragraph 1 of UNCLOS.
In February 1992, China officially announced and implemented the Law of the People’s Republic of China on the Territorial Sea and the Contiguous Zone (Chinese Territorial Sea Law). Based on Articles 3 and 7 of UNCLOS, Article 3 of the Chinese Territorial Sea Law stipulates the establishment of the 12 nautical miles rule and the method of straight baselines. Moreover, Article 8, paragraph 2 of the Chinese Territorial Sea Law states that “foreign ships for military purposes shall be subject to approval by the Government of the People’s Republic of China for entering the territorial sea of the People’s Republic of China.” As noted, China has adopted a prior permission system for entry and passage into its territorial waters by foreign warships.
Generally, it is the country that possesses the right that decides whether to exercise that right and how to exercise it. But China’s adoption of a prior permission system denies the right of innocent passage by warships, and as such is a violation of UNCLOS.
UNCLOS gave the title “Rules Applicable to All Ships” to Subsection A at the start of Part 2, Section 3, “Innocent Passage in the Territorial Sea.” Article 17 then states that “ships of all States… enjoy the right of innocent passage.” The title for Subsection B is “Rules Applicable to Merchant Ships And Government Ships Operated for Commercial Purposes,” while the title for Subsection C is “Rules Applicable to Warships And Other Government Ships Operated for Non-Commercial Purposes.” From this, it is clear that “All Ships” in Subsection A includes warships and government ships. Regarding the standard for determining “innocent” in the right of innocent passage, UNCLOS adopts an activity and conduct-based standard to objectively determine whether a vessel is innocent or not, based on its activities while in territorial waters, rather than based on the type, equipment, cargo, or destination of a vessel. Additionally, Article 19, paragraph 2 of UNCLOS lists 12 activities that negate the innocent nature of a passage, including activities that can only be conducted by warships, including the use of force or military exercises.
For this reason, the UNCLOS system is based on the assumption that warships possess the right of innocent passage.