MANILA (Reuters) - Thousands of Filipino and American soldiers began annual war games on Monday, the first under a new security pact with the United States, focusing on maritime security in the face of China's growing naval presence in the disputed South China Sea.
The joint exercises "Balikatan" (shoulder-to-shoulder) would test the combat readiness of the two oldest allies in this part of the world to respond to any maritime threats, including piracy and humanitarian assistance and disaster response.
The new security pact was signed last week just hours before U.S. President Barack Obama visited. Obama said the agreement was a testament to Washington's "pivot" to Asia and was an "ironclad" commitment to defend the Philippines.
The Philippines has territorial disputes with China over the South China Sea, which is said to be rich in deposits of oil and gas and carry about $5 billion in ship-borne trade every year.
The Spratlys in the South China Sea are also claimed by Taiwan, Vietnam, Malaysia and Brunei.
"Tensions in Asia-Pacific region have increased due to excessive and expansive maritime and territorial claims, undermining the rule of law," Foreign Affairs Secretary Albert del Rosario said at the opening ceremony at the main army base in Manila.
"The aggressive patterns of behavior aimed at changing the status quo threaten peace and stability in the region. Balikatan 2014 with its focus on maritime security strongly supports our capabilities to address these challenges."
On Saturday, a navy plane dropped food and water to troops stationed on a transport ship that ran aground on the disputed Second Thomas Shoal in the South China Sea. Chinese coast guard ships have set up a blockade around the shoal.
Nearly 5,500 American and Filipino troops are taking part in the two-week drills in different parts of the main island of Luzon. The war games will see U.S. F-18 fighters rehearse bombing runs and troops involved in live fire drills.
Under a new security pact, the Enhanced Defence Cooperation Agreement, signed last week during Obama's visit, the U.S. will have wider access to local bases and construct facilities to store supplies and equipment for 10-years in exchange for increased support on maritime security and humanitarian assistance.
The annual war games come under the 1951 Mutual Defense Treaty, part of a web of security alliances the United States built in the Asia-Pacific region during the Cold War.
Outside the main army base in Manila, dozens of Left-wing activists protested, saying the Americans are using China as a bogeyman to gain a forward base in the Philippines.
"It is silly that China is even being mentioned since the U.S. has expressed its non-committal to defend the Philippines in the event of an armed confrontation with China," said Renato Reyes, Bayan (Nation) secretary-general.
(Reporting By Manuel Mogato; Editing by Michael Perry)