| ULUGAN BAY, Philippines
ULUGAN BAY, Philippines American and Philippine troops waded ashore on Wednesday in a mock assault to retake a small island near disputed areas in the South China Sea, an exercise expected to raise tension with rival claimant China.
Last week, China's military warned the United States that U.S.-Philippine military exercises have raised risks of armed confrontation over contested waters in the South China Sea, the toughest high-level warning yet after weeks of tension.
The United States and the Philippines launched two weeks of annual war games on the western island of Palawan amid the standoff near Scarborough Shoal in another part of the South China Sea, west of a former U.S. navy base at Subic Bay.
"Never was China ever mentioned in our planning and execution," Lieutenant General Juancho Sabban, commander of military forces in the western Philippines, told reporters.
The military drill "simply means we want to work together, improve our skills", he said.
"China should not be worried about Balikatan (shoulder-to-shoulder) exercises," he said. Sabban has jurisdiction over the disputed Spratly Islands and Reed Bank, where the Philippines is due to open oil-and-gas exploration bids on Friday.
Almost a hundred American and Philippine troops were launched from U.S. and Philippine ships in a simulated amphibious assault to recapture an island supposedly taken by militants.
Four days ago, commando teams rappelled down from U.S. helicopters and landed from rubber boats in a mock assault to retake an oil rig in northern Palawan, 18 km (11 miles) off the town of El Nido on the South China Sea.
The annual war games come under the 1951 Mutual Defense Treaty (MDT), one of the web of security alliances the United States built in the Asia and Pacific region during the Cold War.
The drills are a rehearsal of a mutual defense plan by the two allies to repel any aggression in the Philippines.
Hundreds of miles to the north, a Philippine coast guard ship patrols near disputed Scarborough Shoal, a group of half-submerged rock formations 124 nautical miles west of the Philippines' main Luzon island.
Philippine and Chinese ships are often in the same areas of the South China Sea, with two Chinese maritime surveillance ships a few miles away from the coast guard vessel and five Chinese fishing boats hauling clams, coral and sharks nearby.
(Editing by Ed Lane and Paul Tait)
(This story was corrected to remove the incorrect reference to thousands of troops in the first paragraph, and the number of troops in the seventh paragraph)