TOKYO — U.S. and allied forces are gathering in thePhilippines this week for joint military exercises as a show of force to counter China's controversial territorial claims in the South China Sea.
More than 5,000 U.S., Philippines and Australian troops will take part in the annual Balikatan(shoulder-to-shoulder) training exercises, which began Monday and runs through April 16. The training include amphibious warfare drills and disaster relief operations.
The exercises are taking place across the Philippines, including the island ofPalawan near the disputed Spratly Islands, where China has built a string of artificial islands. China, the Philippines, Vietnam, Malaysia, Taiwan and Brunei have competing territorial claims in the waters.
Although Japan will not take part directly in the exercises, two Japanese warships and a submarine began a four-day goodwill visit to the Philippines on Sunday. It is the first time that a Japanese submarine has visited the Philippines in more than 15 years, and comes just a week after new laws in Japan eased longstanding restrictions on the country’s armed forces.
A United Nations-sponsored tribunal in The Hague is expected to rule on a Philippines challenge to China’s sovereignty claims within the next few weeks. China says the tribunal does not have authority and has boycotted the case.
In addition to asserting sovereignty over virtually all of the islands and waters of the South China Sea, China has claimed a group of uninhabited islands in the East China Sea that has been administered by Japan since the late 1800s. That has roiled relations with Tokyo, as well.
The South China Sea includes some of the world’s most important sea-lanes: about $5 trillion in trade passes through the region annually.
The Obama administration worries that China could use the new islands to restrict air and sea navigation because some now include military-grade airstrips, ports and other modern infrastructure.
To underscore its right to free navigation in the waters, the U.S. military has twice sent U.S. warships to conduct exercises near China’s new islands since last fall, drawing sharp criticism from China.

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U.S. Defense Secretary Ashton Carter plans to visit the Philippines next week to view part of the exercises. It will be the first time that a U.S. Defense secretary has directly observed the exercises, which have held annually since the 1980s.
In January, an Enhanced Defense Cooperation Agreement went into effect that will give U.S. troops regular access to five military bases in the Philippines.
A spokesman for China’s Ministry of National Defense, last week accused the United States of bringing a  “Cold War mentality” to the region. “The U.S. has come back and reinforced its military presence in the Philippines and promoted the militarization in the South China Sea,” Yang Yujun said.
The U.S. has little choice but respond forcefully, said Sean King, an East Asia specialist with the Park Strategies consulting firm, in New York. “Sadly, Beijing only understands force and resolve. It's good that our allies know we have their backs,” King said.
Japan has agreed to sell the Philippines short-range reconnaissance aircraft and patrol boats, and Defense Minister Gen Nakatani is expected to visit later this month to discuss further support.
After leaving Manila on Wednesday, the Japanese warships will make a port call in Vietnam, sailing through the South China Sea to get there.
Tetsuo Kotani, senior fellow at the Japan Institute for International Affairs, in Tokyo, said he expects Japan to increase its military presence in the region.
“The Balikatan exercise, the Japan Maritime Self Defense Force port calls, the U.S. Navy’s freedom of navigation operations are all are necessary, but still insufficient to shape China's behavior,” he said. “There will be no short-term and long-term resolution for maritime disputes as China is challenging the existing rules-based regional system.”