In late September, the Yomiuri Shimbun (Japan’s largest circulation newspaper) reported that the Japan Maritime Self-Defense Force (JMSDF) destroyer Sazanami (JS Sazanami, DD-113) had navigated north to south through the Taiwan Strait, located between the Chinese mainland and Taiwan. The vessel had transited the Taiwan Strait en route to joint multinational training exercises with the U.S., Australia, and New Zealand in the South China Sea, in what was the first instance of a JMSDF destroyer traveling through the Taiwan Strait. According to the article, the transit of the Sazanami through the Taiwan Strait was based on orders from then Prime Minister Kishida Fumio.
The U.S. and Japan consider the central part of the Taiwan Strait to be international waters, meaning military vessels may freely transit those waters. China, however, strongly opposes the transit of European or American military vessels through the Taiwan Strait.
The Taiwan Strait, which separates the Chinese mainland from Taiwan, is between 85 to 105 nautical miles wide. The irregular and meandering coastline along the mainland offers good sites for harbors and anchorages.
If the distance between the low-water line of the Chinese mainland and its coastal islands and the low-water line of Taiwan and the Penghu Islands on the other side of the Taiwan Strait are set as the baseline (territorial sea baseline) for territorial sea, then there would exist a “non-territorial waters corridor” in the central part of the Taiwan Strait that is about 50 to 80 nautical miles wide. This corridor is located outside the internal waters and territorial sea that are subject to the sovereignty of China and Taiwan.
In simple cases where the coastline is relatively straight, the normal baseline is used to establish a territorial sea baseline. Article 5 of the UN Convention on the Law of the Sea (UNCLOS) establishes that “Except where otherwise provided in this Convention, the normal baseline for measuring the breadth of the territorial sea is the low-water line along the coast as marked on large-scale charts officially recognized by the coastal State.” The low-water line is the territorial border between the land and the surface of the sea at low tide when the waters recede.
However, China has established a territorial sea baseline along the mainland side of the Taiwan Strait using a straight baseline. Straight baselines are used when a coastline is irregular, making it difficult to apply the normal baseline as-is, including when coastal indentation is considerable. This method takes suitable points along the outermost coastline as the outer land boundary and connects these points with straight lines to form a baseline.
China adopted the “Law of the People’s Republic of China on the Territorial Sea and Contiguous Zone” in February 1992. This law established the straight baselines method for determining the 12 nautical mile-wide territorial sea. Article 3, Section 1 of this law states that the breadth of the territorial sea of China will be measured in nautical miles and measured from the baselines of the territorial sea. Section 2 prescribes the establishment of the territorial sea baseline by using straight lines to connect multiple points. This law does not reference the normal baseline using low-water lines, referencing only straight baselines. However, it does not indicate (or disclose) the points that would be used to actually establish straight baselines.
Later, in 1996, China announced the “Declaration of the Government of the People’s Republic of China on the Baselines of the Territorial Sea,” establishing straight baselines along the coastlines of the Taiwan Strait and the Paracel Islands. This declaration did include a list of geographical points of longitude and latitude used to establish straight baselines. 49 points along the mainland coastline and 28 along the coastline of the Paracel Islands were identified.
However, the minimum width of the central non-territorial waters corridor of the Taiwan Strait differs only slightly between the baseline setting utilizing straight baselines and the one using low-water lines.
When there are straits like the Taiwan Strait that feature non-territorial waters corridors in the middle of the strait that are outside the internal waters and territorial seas under the sovereignty of coastal countries, military vessels are free to navigate through the corridor. Even if the non-territorial waters corridor falls within the coastal country’s contiguous zone or exclusive economic zone (EEZ), this does not fall under the sovereignty of the coastal country and as such does not alter a military vessel’s right to transit the corridor.
It should be noted that the Taiwan Strait is not an international strait with the right of transit passage as defined by UNCLOS.
During the process of drafting UNCLOS, the U.S., the former Soviet Union, and other countries using straits for passage expressed concerns that setting the maximum width of territorial sea at 12 nautical miles would mean that straits that used to allow free passage by foreign vessels as international waters (outside territorial sea) would fall within the territorial sea of coastal states, consequently only innocent passage of these territorial sea would be allowed, and foreign submarines would be required to traverse these waters while at surface level.
As a result of concessions made between strait-using countries and coastal countries, UNCLOS granted all vessels and aircraft (including military vessels and aircraft) the right of transit passage, allowing “freedom of navigation and overflight” for “continuous and expeditious transit” of the [international] strait. While vessels passing through international straits must adhere to certain regulations, they are guaranteed freedom of passage, and their passage is not required to be innocent.
Within the non-territorial waters corridor in the middle of the Taiwan Strait, foreign vessels and aircraft (including foreign military vessels and aircraft) are guaranteed freedom of passage without exercising either the right of innocent passage within territorial sea or the right of transit passage through international straits.
TSURUTA Jun is an associate professor at Meiji Gakuin University.
