Chinese governments since ancient times have never given up the exericise of its jurisdiction over South China Sea islands

A series of recent actions taken by Vietnam to disturb and play up the normal drilling of Haiyang Shiyou 981, an oil rig owned by China National Offshore Oil Corporation, in the waters off China's Xisha Islands has put tensions in the South China Sea in the spotlight of worldwide attention.

Hanoi should know that such drilling in the said area is China's sovereign right endowed by the United Nations Convention on the Law of the Sea.

First, the Xisha Islands have been a Chinese territory since ancient times. Available historical documents record that Chinese people first discovered the South China Sea islands in the Han Dynasty (202 BC-AD 220) and also gained an initial knowledge about the South China Sea. With the progress of the navigation technology and the invention and wide use of compass, the navigation and activities of Chinese people at sea tended to be more frequent from the Song Dynasty (960-1279). Since then, South China Sea islands and adjacent waters have not only become a wide area for Chinese people to engage in production and commercial activities, but have also become an important water area for China's navy forces to patrol and defend. In AD 971, Zhao Kuangyin, the founding emperor of the Song Dynasty, began organizing a patrol naval squad, whose regular cruises and patrols in the South China Sea established China's jurisdiction over the Xisha Islands. In 1279, Kublai Khan, the founding emperor of the Yuan Dynasty (1271-1368), sent General Guo Shoujing to the South China Sea for the inspection and research of the sea's geography and landscape to offer security guarantees for the cruising imperial naval force. Afterwards, the Ming (1368-1644) and Qing (1644-1911) dynasties both put the South China Sea islands and adjacent waters under their jurisdiction, and it has ever since become a common practice for China's naval forces to make inspection tours for coastal defense and exercise sovereignty over them. There were also countless maps, archives, documents and logs reserved from the Ming and Qing dynasties that recorded the South China Sea islands.

The traces of Chinese people's activities from ancient times have also left numerous remains of historical relics there. Aside from the sites of historical relics, quite a few stone tablets erected during the Qing Dynasty and the Republic of China (1912-1949) on South China Sea islands and reefs to maintain and declare China's sovereignty over them have also been excavated. Most of these stone tablets were the monuments of then Chinese government officials or military officers who landed on these islands or reefs for inspections.

During the period of the Republic of China, the Chinese government took a series of active measures maintaining its sovereignty over the South China Sea islands, including the renaming of islands and reefs at the sea, including the Xisha Islands, by the government agency in charge of maps censorship. After World War II, China resumed its exercise of sovereignty over the South China Sea islands in accordance with the spirits of a series of international documents, including the Cairo Declaration and Potsdam Proclamation. From November to December 1946, the government of then the Republic of China sent Yongxing, Zhongjian, Taiping and Zhongye warships to the South China Sea for taking over the sovereignty of Xisha, Dongsha, Zhongsha and Nansha islands that had been grabbed by Japan during World War II. In February 1948, the government of the Republic of China published an official map, The Location of South China Sea Islands, which explicitly marked South China Sea islands, including the Xisha Islands, as a part of China's territory.

China has continued exercising its sovereignty over the Xisha Islands since the founding of the People's Republic of China in 1949. Following the signing of a so-called peace treaty between Western countries led by the United States and Britain with Japan at the San Francisco Conference, then Foreign Minister Zhou Enlai issued a statement in the capacity of the Chinese government in 1951, explicitly pointing out that the Xisha Islands and Nanwei Island, which is affiliated to the Nansha Islands, are both Chinese territories like the entire Nansha, Zhongsha and Dongsha Islands and that the Chinese government had formally taken over their full sovereignty from Japan after its surrender, although these islands had once fallen into the hands of Japanese imperialists during their aggressive war against China. In the statement, Zhou made China's stance clear that China's sovereignty over Xisha and Nansha islands is free from any restraints of the US and Britain-led "peace treaty" with Japan. In 1958, the Chinese government issued a statement, once again claimed that the Dongsha, Xisha, Zhongsha and Nansha islands as a part of Chinese territory. Following the statement, then Vietnamese prime minister Pham Van Dong sent a verbal note to then premier Zhou Enlai, solemnly expressing that the Vietnamese government "recognizes and endorses" the Chinese government's statement. In 1959, the Chinese government set up an office on the Yongxing Island in charge of the affairs of the Xisha, Nansha and Zhongsha Islands, and the office was administratively put under Guangdong province. In 1988, the office was assigned under the newly established Hainan province. The Law of the PRC on the Territorial Sea and the Contiguous Zone, a law that was passed in 1992, once again reiterated China's stance that the sovereignty of South China Sea islands, including the Xisha Islands, belongs to China. What is notable is that countries surrounding the South China Sea always definitely recognized China's sovereignty over these islands in the years before the 1970s.

Second, sovereignty over the Xisha Islands includes sovereignty over their territorial waters, contiguous zone, exclusive economic zone and continental shelf. According to Article 121 of the UN Convention on the Law of the Sea, the territorial sea, the contiguous zone, the exclusive economic zone and the continental shelf of an island are determined in accordance with the provisions of this Convention applicable to other land territory. In May 1996, the Chinese government issued a statement on the baseline of its territorial sea, declaring the baseline of its Xisha Islands as a straight baseline. This, together with the UN Convention and relevant laws of China's own, shows the Chinese government has the right to lay claim to the waters extending 12 nautical miles away from the straight baseline of the Xisha Islands, their contiguous zone, exclusive economic zone and continental shelf.

Third, the drilling of a CNOOC oil rig in the waters off the Xisha Islands should be China's sovereign right that accords with the UN Convention on the Law of the Sea. According to the Convention, territorial sea is an extension of a coastal nation's territorial sovereignty and it thus enjoys sovereignty over its territorial sea, corresponding overhead space, seabed and subsoil. The nation is privileged to exercise jurisdiction over customs, finance, immigration and healthcare in its contiguous water areas. The UN Convention also extends to the nation a sovereign right for the exploration, development, maintenance and management of seabed or underground natural resources in its exclusive economic zone as well as the right for some economic activities, such as the utilization of seawater, ocean currents, and wind power. The nation also enjoys jurisdiction over the construction and use of artificial islands and related facilities, oceanic researches, and protection of oceanic environment. At the same time, the country can also exercise its right over its continental shelf and enjoy exclusive rights for the exploration and development of natural resources at the continental shelf and any other country is not empowered to engage in similar activities at the continental shelf if no explicit nod is gained from the nation. According to the UN Convention, coastal countries also enjoy an exclusive right for the drilling at their continental shelf whether or not they have acquired an effective or symbolic occupation of the shelf or whether or not they have issued an explicit announcement for this purpose.

All these stipulations contained in the UN Convention on the Law of the Sea indicate that China owns the right for exploration and management of the waters off its Xisha Islands and that the drilling of the CNOOC oil rig is completely a sovereign right accorded by the convention.

Last, the drilling of the CNOOC oil rig is by no means within Vietnam's exclusive economic zone or on its continental shelf, as claimed by Hanoi. Undeniably, as a coastal nation, Vietnam can also make its claims on its exclusive economic zone and continental shelf. As two neighboring coastal countries, there do exist some overlapping claims between China and Vietnam in terms of their EEZ and continental shelf. As early as in December 2000, China and Vietnam signed an agreement on the delimitation of their EEZ and continental in the Beibu Gulf waters, an accord that only confirmed the delimitation of the Gulf while leaving bilateral delimitation in other waters unresolved. However, the drilling site of the CNOOC oil rig is only 17 nautical miles away from China's Zhongjian Island, but 150 nautical miles from the coastline of Vietnam, a fact that decides that the site is indisputably inside China's territorial waters no matter how the waters of both countries will be delimitated. Such an iron-clad fact is enough to testify that Vietnam's claim that the drilling of the Chinese oil rig is inside its EEZ and continental shelf is completely groundless.

Facts prove that the drilling of the CNOOC oil rig in the waters off China's Xisha Islands is a legitimate activity the country is empowered to conduct in accordance with the UN Convention on the Law of the Sea. Just as Hua Chunying, spokesperson of the Ministry of Foreign Affairs, said at a recent press briefing, the drilling of the CNOOC oil rig is conducted completely in the waters off China's Xisha islands. The provocative actions taken by Vietnam, such as sending ships to ram into China's vessels at the site, not only violate the UN Convention on the Law of the Sea, but also infringe on China's sovereignty and jurisdiction as well as its relevant domestic laws.

Vietnam should immediately stop any interruptive activities and undertake corresponding consequences and international responsibilities for its provocations.

The author is a law professor with Wuhan University.