TOKYO — An international tribunal will issue a long-awaited ruling Tuesday in a case brought by the Philippines over China’s vast territorial claims and island-building in the South China Sea.

The ruling from the Permanent Court of Arbitration in The Hague, Netherlands, will be the first to address competing claims and interests among a half-dozen countries fronting the South China Sea. It also comes as U.S. and Chinese warships engage in an increasingly tense game of cat and mouse in the disputed waters.

China has claimed virtually all of the South China Sea, a crucial waterway used for an estimated $5 trillion in annual trade.

The Philippines filed suit with the Hague tribunal in 2013, after China seized a rich fishing region known as the Scarborough Shoal. The Philippines claims that area as part of its exclusive economic zone.

The suit alleges that China’s extensive claims in the sea do not conform to the United Nations Convention on the Law of the Sea, which governs certain maritime claims and conduct.

China has refused to participate in the case or abide by Tuesday’s ruling, claiming the tribunal lacks jurisdiction.

The ruling “amounts to nothing more than a piece of paper,” former Chinese State Councilor Dai Bingguo told a conference in Washington, D.C., last week. “China will grip its own future on issues of territorial sovereignty and will never accept any solution imposed by a third party.”

China has backed its claims by building a chain of landfill islands in contested waters. Some include military-grade runways, deep-water ports and extensive land facilities. China also has boosted naval activities throughout the region.

The United States says it does not take sides in individual sovereignty disputes, but has called the new islands a “Great Wall of Sand” and expressed concerns they could be used as military bases for China to restrict air and sea navigation.

China has pledged not to do that.

Nonetheless, U.S. warships have sailed within close proximity of Chinese-built islands at least three times since late 2015 in “freedom of navigation operations.” The U.S. has promised more operations.

Chinese warships have responded by tailing U.S. vessels throughout the South China Sea and ordering U.S. ships and planes to steer clear of the new islands.

In one recent case, Chinese intelligence-gathering ships followed a U.S. carrier battle group — within visual range, around the clock — for the entirety of its three-month patrol in the South China Sea.

China Foreign Ministry spokesperson Hong Lei said last week that China has “indisputable sovereignty over the South China Sea Islands and the adjacent waters,” based on “historical practices of the Chinese people and the government.”

The South China Sea is 50% larger than the Mediterranean Sea and dotted with shallow reefs, rocks and shoals. It also is believed to hold extensive deposits of minerals and other natural resources.

Taiwan, Vietnam, Brunei and Malaysia also have overlapping claims. China has said it is willing to negotiate with each claimant separately, but not together, a strategy that could give China more leverage in negotiations with its smaller neighbors.

China’s navy completed a weeklong series of exercises Monday in the disputed waters that brought together nearly 100 warships and dozens of fighter planes.

A U.S. aircraft carrier battle group and a separate U.S. “surface action group” have also been operating in the South China Sea in recent weeks.

Grant Newsham, senior research fellow at the Japan Forum for Strategic Studies in Tokyo, said The Hague tribunal’s ruling will make little difference to the realities on the ground — or  on the water.

“China will continue its successful effort to assert physical domination over the South China Sea, with the political and psychological dominance that comes with it,” Newsham said.

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