Disputes during the Cold War
Since mid-1950s, the Philippines and South Vietnam started their encroachment of the Nansha Islands. In 1956, Tomas Cloma, a Filipino adventurer announced his discovery of a group of islands in the Nansha waters, and renamed them "Freedomland". Shortly after, the Philippine government argued that these Islands should belong to their country on the grounds of the "Cloma discovery", and threatened to take over the islands immediately. Obviously aware of the Taiwan authority’s position on the sovereignty over the islands, Manila even intended to send a delegation to Taiwan to discuss the matter. Since 1962, South Vietnam occupied Nanzi Cay (South West Cay), Dunqian Cay (Sandy Cay), Hongxiu Island (Namyit Island), Jinghong Island (Sin Cowe Island), Nanwei Island (Spratly Island), and Anbo Cay (Amboyna Cay), which was strongly objected and protested by both sides of the Taiwan Straits.
A bigger wave of encroachment happened in the 1970s and 1980s, under the influence of the discovery of rich oil and gas reserves on the continental shelve of the South China Sea by the US and a number of UN survey agencies in the late 1960s, and the signing of the United Nations Convention on the Law of the Sea (the Convention) in 1982, which introduced the 200 nautical mile exclusive economic zone (EEZ) regime.
Greatly incentivized by a high potential for resource exploration, Vietnam, the Philippines and Malaysia set their sights on islands and reefs in the Nansha Islands.
North Vietnamese regime had openly recognized China's sovereignty over the South China Sea islands, but soon abandoned this policy after its unification of Vietnam. In 1975, North Vietnam, on the pretext of "liberation", occupied six islands and reefs of the Nansha Islands which were formerly seized by South Vietnam. Later, it seized another 18 islands and reefs, including Ranqingsha Reef (Grierson Reef) and Wan’an Bank (Vanguard Bank). On March 14, 1988, Vietnam had a skirmish with China in waters near China’s Chigua Reef (Johnson South Reef).
The Philippines occupied 8 islands and reefs, including Feixin Island (Flat Island) and Zhongye Island (Thitu Island); Malaysia seized Danwan Reef (Swallow Reef), Nanhai Reef (Mariveles Reef) and Guangxingzai Reef (Ardasier Reef).
At the same time, these countries dramatically altered their original stance on the issue of the Nansha Islands. By formulating national laws of the sea and issuing political statements, they officially asserted sovereignty over the Nansha Islands and made claims on the territorial waters surrounding the Nansha Islands.
At the same time, US clearly demonstrated its acknowledgment of China’s sovereignty over the Nansha Islands in its diplomatic inquiries, measurement requests and flight plan notifications. In addition, the Taiwan authorities have also received the American military personnels on Nansha Island where it stationed forces. For a long period of time, the US remained silent to the encroachments by the Philippines and Vietnam, but it did consulted the Taiwan authorities on many occasions related to the sovereignty issue over these islands and reefs. From February 1957 to February 1961 the US Government made multiple application requests to the Taiwan authorities to allow the US Air Force based in the Philippines to conduct nautical chart measurement and meteorological surveys in the vicinity of Huangyan Island (Scarborough Reef) and the Nansha Islands, obviously acknowledging China's sovereignty over these islands through the role of the Taiwan authorities. Such acknowledgment was confirmed in books and maps published around this time such as Columbia Lippincott Gazetteer of the World (1961), Worldmark Encyclopedia of the Nations (1963), and Constitutions of the Countries of the World (1971), all of which clearly state that the Nansha Islands belong to China. Indeed, the US policy-makers faced a dilemma at that time: on one hand, out of a moral commitment to its Chinese Nationalist ally in Taiwan, and in accordance with international law, the US should have announced these features as Chinese territory; on the other hand, out of its anti-communism policy and Asia-Pacific strategy, it could not possibly recognize Mainland China as their rightful owner, nor did it want to hurt its relations with its important allies, such as the Philippines, through such recognition.
As far as China is concerned, over the years, only the Taiwan authorities had station forces on Taiping Island. It’s not until the late 1980s in the 20th century when the mainland China started to take control over six minor islands and reefs. In 1994, China built fishery and sheltering facilities on Maiji Reef.