(CNN)The Philippines will provide the United States with expanded access to its military bases, the two countries said Thursday, providing US forces with a greater strategic footing on the southeastern edge of the South China Sea close to self-ruled Taiwan.
The newly announced deal will give the US access to four more locations under an Enhanced Defense Cooperation Agreement (EDCA) dating to 2014, allowing the US to rotate troops to a total of nine bases throughout the Philippines.
The US has stepped up efforts to expand its Indo-Pacific security options in recent months, amid mounting concerns over China's aggressive territorial posturing throughout the region.
Speaking during a visit to Manila Thursday, US Defense Secretary Llyod Austin said the US and the Philippines remained committed to strengthening their mutual capacities to resist armed attack.
"That's just part of our efforts to modernize our alliance. And these efforts are especially important as the People's Republic of China continues to advance its illegitimate claims in the West Philippine Sea," said Austin, referencing China's increased presence in waters close to the Philippines.
Austin did not give the location of the bases to which the US military will gain new access.
China warned of heightened tensions in the region following the move. The Philippines allowing US access to four defense sites on its territory has "escalated tension in the region and endangers regional peace and stability," Chinese foreign ministry spokesperson Mao Ning said on Thursday.
"Out of its selfish agenda, the US side has held up to the cold war. Regional countries should remain vigilant about this and avoid being used by the US," Mao said.
Thursday's announcement follows a spate of high-profile US military agreements throughout the region, including plans to share defense technologies with India, and plans to deploy new US Marine units to Japanese islands.
The US Marine Corps also opened a new base on Guam last week, a strategically important US island east of the Philippines. The location, known as Camp Blaz, is the first new Marine base in 70 years and one day is expected to host 5,000 Marines.
Moves to counter China
Increased access to military bases in the Philippines would potentially place US armed forces fewer than 200 miles south of Taiwan, the democratically ruled island of 24 million that the Chinese Communist Party claims as part of its sovereign territory despite never having controlled it.
Chinese leader Xi Jinping has refused to rule out the use of military force to bring Taiwan under Beijing's control, but the Biden administration has been steadfast in its support for the island as provided by the Taiwan Relations Act, under which Washington agrees to provide the island with the means to defend itself without committing US troops.
In November, US Vice President Kamala Harris visited the Philippines to discuss expanded US base access with the recently elected President Ferdinand "Bong Bong" Marcos Jr. Some experts said her visit sent an unambiguous message to Beijing