The ongoing US-Philippines military drill, which apparently targets China, and the predicted passage of US Navy vessels near China's Nansha Islands are designed to serve US interests at the cost of China's, observers said.
Manila is eager to expand its territory to China's Meiji Reef in the South China Sea, said Yang Xiyu, a research fellow at the China Institute of International Studies, and the US "might use its joint drill with the Philippines to show support for the expansion."
"It's highly possible that US forces will choose Meiji Reef for their passage," he added.
Reuters cited an unnamed source on April 2 as saying that the US Navy plans to send ships through a passage near Meiji Reef this month, the third in a series of such challenges that have drawn sharp criticism from China.
The US has conducted so-called freedom of navigation exercises in recent months, sailing near Zhubi Reef, part of the Nansha Islands, and Zhongjian Island, part of the Xisha Islands.
The scale and number of vessels sailing near the reef are not likely to be lower than the previous two challenges undertaken by US destroyers, Yang said.
Yin Zhuo, director of the People's Liberation Army Navy's Expert Consultation Committee, said Washington is using the South China Sea issue to endanger Beijing's ties with its neighbors and to draw Japan, the Philippines and Australia into a collective containment of China.
The move will lead to escalated tensions in the region, he said.
A small contingent of Australian troops will join the exercises, while Vietnam and Japan have sent officers in an observer capacity.
"Eager to undercut China's mounting regional influence, some specific nations take delight in sowing seeds of discord between China and rival claimants, and boosting their military presence and patrols to thwart China in the name of safeguarding freedom of navigation," Xinhua News Agency said in a commentary.
about 8,000 US and Filipino troops have been engaged in the annual, 11-day military exercise since April 4.
US Defense Secretary Ash Carter will observe the drill after arriving next week, the first US defense chief to do so, Reuters said.
Manila played down any suggestion that the Balikatan ("Shoulder-to-Shoulder") exercise, which will simulate retaking an oil-and-gas platform and practice an amphibious landing, targeted any specific country.
Asked if the drill's scenarios include a potential security crisis in the South China Sea, Lieutenant-General John Toolan, commander of US Marine forces in the Pacific, said, "It does, absolutely," according to Reuters.
Toolan said a mobile rocket system that has been deployed in various areas, including Afghanistan, will be used during the exercise for the first time. "We can move this stuff anywhere we need to."
Rene de Castro, an international studies professor at De La Salle University in Manila, told Agence France-Presse that the drills appeared to have China's presence in the South China Sea in mind.
"Looking at the features of Balikatan — the mobile missile-launchers, the fighter planes — that is an indication that the alliance is being geared for territorial defense," he said.
President Xi Jinping told US President Barack Obama on March 31 during their meeting on the sidelines of the nuclear summit in Washington that China would not accept any behavior under the guise of freedom of navigation that violates its sovereignty.