Editor's note: China has faced simmering tensions with neighboring countries over a string of territory disputes in the South China Sea, raising concerns that the area is becoming a source of conflict which could have global significance.

What and where is the South China Sea?

The nine-dotted line used by China for its claim to the South China Sea.

The semi-enclosed South China Sea, one of the three Asian marginal seas, lies between the Pacific Ocean and the Indian Ocean. It encompasses an area of 3.6 million square kilometers from the Singapore and Malacca Straits to the Strait of Taiwan, stretching more than 1,800 kilometers from north and south and 900 kilometers from west to east.

The nine-dotted line, U-shape line, or nine-dash map (literally, "Nine division lines of the South China Sea") refers to the demarcation line used by China for its claim to the South China Sea, an area including the Xisha Islands, Dongsha Islands, Zhongsha Islands, James Shoal, Nansha Islands, and Huangyan Island.

Alongside the fully fledged islands, there are dozens of uninhabited rocky outcrops, atolls, sandbanks and reefs.

The area's significance largely lies in the fact that one-third of the world's shipping passes through its waters, and that it is believed to hold huge reserves of oil and gas beneath its seabed.

What is the dispute about?

The South China Sea issue refers to the disputes over territorial sovereignty, maritime delimitation and resource allocation among China and a number of southeastern Asian countries. Most of the disputes center on the Nansha Islands, so the "South China Sea issue" is also called the "Nansha Dispute."

The global financial crisis hit Southeast Asia in 2008, raising the cost of living and lowering living standards there. To prevent the economic crisis from turning into social unrest, some neighboring countries chose to divert domestic tensions by hyping the so-called “China threat” and territorial disputes in the South China Sea.

The recent conflict between China and the Philippines centers on the territorial claim of the Huangyan Island.

The escalation of the disputes between China and other rival countries on island sovereignty and maritime demarcation has received increased attention from both ASEAN and Western countries, including the U.S. and Japan, making the South China Sea issue a global flashpoint.

What is China's claim?

China demarcates its claims within the nine-dotted line, which first appeared in "South Sea Islands Location Map” released by the Chinese government in February 1948.

Ancient Chinese mariners discovered the Nansha Islands as early as the second century BC. With the development of the maritime industry, the Nansha Islands started to attract attention. China renamed the South China Sea islands "Changsha" during the Tang and Song dynasties (618-1279).

The Chinese people were the first to develop and manage the Nansha Islands. The Odds Contents of the 1st century BC and the Guangzhou Records by the Jin-dynasty Pei Yuan recorded Chinese fishermen's activities in the South China Sea. In the Ming and Qing dynasties (1368-1911), more Hainan Island fishermen made their way to the Nansha Islands for fishing, and fixed shipping operation lanes took shape. At this time, the fisherman reclaimed the land and planted trees.

In the 19th century, foreign navigators, based on the existing facts, admitted that the Chinese had originally developed and managed the Nansha Islands. "Hainan fishermen, dotted on every island, live on sea cucumbers and shellfishes. Some of them also inhabit the islands," noted the British Navy's China Sea Guide.

China was the first country that exercised jurisdiction on the South China Sea. The Zheng He Navigational Charts of the Ming Dynasty clearly record the Nansha Islands. Two Qing-dynasty maps, one dating from 1716 and the other 1817, also include the Nansha Islands, calling them "Wanli Shitang". In 1883, Germany stopped its investigation activities on the Nansha Islands in the face of protests from the Qing government. In 1933, the French occupation of the Nansha Islands met with resistance from Chinese fishermen, after which the Chinese government made firm its claim to the territory, which resulted in France's eventual retreat. In 1946, the Chinese government, according to the "Cairo Declaration" and "Potsdam Proclamation," regained its sovereignty over the South China Sea islands and reefs and re-erected a monument of sovereignty on the main island.

In 1947, China made public the old and new name table of the South China Sea islands, which were put under the governance of Guangdong Province. In February 1948 the Chinese government released a "South Sea Islands Location Map" which was also re-adopted after the founding of the People's Republic of China. In 1951, the "Japanese Peace Treaty" draft and "San Francisco Conference Statement" announced by Chinese former premier Zhou Enlai pointed out that the "Xisha, Nansha Islands and Dongsha, Zhongsha Islands have always been Chinese territory." In 1958, China proclaimed the "Declaration on the Territorial Sea." Subsequently, in the face of violations by foreign powers, the Chinese government has, on many occasions, reiterated its indisputable sovereignty over the Nansha Islands.

The international community and the dispute-involved countries further confirm China's absolute sovereignty over the South China Sea. According to scores of diplomatic documents, Vietnam has, repeatedly and explicitly, acknowledged the Xisha and Nansha Islands as Chinese territory. Numerous maps published by many countries worldwide, including Romania, Spain and Japan, recognize the Nansha Islands as Chinese territory.

Why is the issue important?

The contest for its huge reserves of resources and its strategic location are the two principal reasons for the South China Sea dispute.

1. Vast resources

The South China Sea has vast reserves of natural resources. There has been little detailed exploration of the area, so estimates are largely extrapolated from the mineral wealth of neighboring areas.

Chinese officials have given the most optimistic estimates of resource wealth in the area. According to figures quoted by the US Energy Information Administration, one Chinese estimate puts possible oil reserves as high as 213 billion barrels – 10 times the proven reserves of the US. But American scientists have estimated the amount of oil at 28 billion barrels.

According to the US Energy Information Administration, the real wealth of the area may well be natural gas reserves. Estimates say the area holds about 900 trillion cubic ft (25 trillion cubic m) – the same as the proven reserves of Qatar.

With the continuous spiraling of global oil prices, some countries have begun to look to the exploitation of the South China Sea area for their future energy supplies.

The area is also one of the region's main shipping lanes, and is home to a fishing ground that supplies the livelihoods of thousands of people.

2. Strategic location

The South China Sea region is one of the busiest sea lanes in the world, through which pass more than half of the world's merchant fleet tonnage, one third of global marine trade volume and half of energy supplies to Northeast Asia, including 80 percent of oil traffic to Japan, South Korea and China's Taiwan region.

From a military perspective, whoever occupies the islands in the South China Sea would directly or indirectly take control of most seaways through the Strait of Malacca as well as those from West Asia, Africa and Europe to East Asia.

Since the end of the cold war, the South China Sea region has become increasingly important, both geopolitically and in terms of marine traffic. With the newfound resources and the United Nations Convention on the Law of the Sea going into effect, some Southeast Asian countries are laying further claims to the islands.