Why the South China Sea Fuels U.S.-China Tensions

Why is the South China Sea such an important point of contention?

Why the South China Sea Fuels U.S.-China Tensions
The Arleigh Burke-class guided-missile destroyer USS Pinckney (DDG 91), left, pulls alongside the fleet replenishment oiler USNS Yukon. (Source: U.S. Navy)

(Bloomberg) -- For decades, the U.S. has guaranteed freedom of navigation in Asia’s waters, patrolling the seas with a view to maintaining the principle that no sovereign state shall suffer interference from another. China’s growing military prowess, combined with a dogged assertiveness over its territorial claims, is testing the old ways and providing a potential flashpoint for the two powers. That tension is felt most keenly in the South China Sea.

1. Where is the South China Sea?

Stretching from China in the north to Indonesia in the south, the waterway encompasses 1.4 million square miles (3.6 million square kilometers), making it bigger than the Mediterranean Sea. It borders countries including Vietnam, Malaysia and Singapore to the west, and the Philippines and Brunei to the east. It’s a thriving fishing zone -- yielding some 10 percent of the global catch -- and holds promising oil and natural gas reserves. Even more noteworthy is the vast amount of trade that transits through its waters. In 2016, that amounted to some $3 trillion, including more than 30 percent of the global maritime crude oil trade. Its economic importance has come into sharper focus because of a brewing trade war between the U.S. and China.

Why the South China Sea Fuels U.S.-China Tensions

2. Why is it such a point of contention?

There are conflicting claims to the seas and rocks, reefs and islands therein. China claims more than 80 percent of the South China Sea and backs up its claim with a 1947 map that shows vague dashes -- the so-called nine-dash line --- looping down to a point about 1,119 miles (1,800 kilometers) south of its Hainan Island. Vietnam, the Philippines, Brunei, Malaysia and Taiwan claim parts of the same maritime area. The Beijing government demands that other countries obtain its consent for military transits near features it occupies, including some it has created by reclaiming land and constructing artificial islands.

3. Where has China built?

China has reclaimed some 3,200 acres (1,290 hectares) of land on seven reefs or rocks in the Spratly archipelago. On them it has constructed ports, lighthouses and runways, and installed missile batteries and other military equipment. Chinese President Xi Jinping told U.S. President Barack Obama in 2015 that China had no intention to militarize the structures. Whenever the installation of a new piece of equipment is revealed, China’s Foreign Ministry says it’s for defense purposes.

4. What does the U.S. say?

The U.S. takes no position on the competing claims by Asian nations. But the U.S. Navy regularly carries out “freedom-of-navigation operations,” known as Fonops, by sending warships and aircraft near disputed waters to demonstrate the right to travel through what it considers international waters and airspace. Through mid-February, the U.S. had carried out 11 publicized Fonops since Donald Trump became president in 2017 -- compared with a total of four in eight years under Obama, according to Ian Storey, a senior fellow at the ISEAS-Yusof Ishak Institute in Singapore.

5. How has the international community responded?

An international arbitration panel in The Hague refuted China’s claims in 2016. It ruled there was no legal basis for China to claim historic rights to resources within seas falling within the nine-dash line. It also found that, under the United Nations Convention on the Law of the Sea, man-made islands -- such as those built by China -- don’t generate maritime entitlements or zones of sovereignty. The case was brought by the Philippines. China refused to take part in the arbitration, saying the panel had no jurisdiction. One former top Chinese diplomat dismissed the ruling as no more than “waste paper.”

6. Why are people worried?

With two great military forces regularly coming into close contact, there are fears that a miscalculation or mistake would risk provoking a more serious confrontation. In 2018, a Chinese warship nearly collided with the USS Decatur while trying to drive it from territory China claims as its own. There was a similar incident eight months earlier. In February, China accused the U.S. of “tricks” as two American warships attempted to assert free navigation rights in the South China Sea.

7. What do the U.S. and China say about these incidents?

U.S. Vice President Mike Pence, referring to the USS Decatur incident, said that despite such “reckless harassment,” the Navy would “continue to fly, sail and operate wherever international law allows and our national interests demand.” Before resigning in December, Secretary of Defense James Mattis said that Beijing would face “larger consequences” in the long term for militarizing the waters that could persuade it to change track. China has responded to Fonops by saying the U.S. is violating its sovereignty.

The Reference Shelf

To contact the reporter on this story: David Tweed in Hong Kong at

To contact the editors responsible for this story: Brendan Scott at, Karen Leigh, Grant Clark

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