(CNN) The Philippines on Monday identified the locations of four new military bases to which the US will gain access as part of an expanded defense deal that analysts say is aimed at countering China.
The four bases include three on the main island of Luzon near Taiwan and one in the province of Palawan in the South China Sea (SCS).
The US has stepped up efforts to expand its security options in the Indo-Pacific in recent months amid growing concerns about China’s aggressive territorial stance across the region.
The new sites, opened under the 2014 Enhanced Defense Cooperation Arrangement (EDCA), will allow the US to deploy troops across a total of nine bases in the Philippines, including on the strategically important island of Balabac near Chinese facilities in the Philippines South China Sea.
U.S. Army soldiers stand next to their humvies before a sharp exercise with Filipino troops at Fort Magsaysay in the Philippines March 31.
“These new locations will enhance the interoperability of the United States and Philippine armed forces and allow us to more seamlessly respond collectively to a number of common challenges in the Indo-Pacific region, including natural and humanitarian disasters,” said the Pentagon’s deputy press secretary Sabrina Singh during a briefing on Monday.
The site announcement follows a spate of high-profile US military deals across the region, including plans to share defense technologies with India and to station new US naval units on Japanese islands.
Earlier this year, the US Marine Corps also opened a new base on Guam, a strategic US island east of the Philippines. The site, known as Camp Blaz, is the first new naval base in 70 years and could eventually house 5,000 Marines.
location of the bases
Although news of the expanded access was announced in early February, the location of the bases remained unknown.
On Monday, the Allies identified the four new sites as Balabac Island in Palawan; Camilo Osias Naval Base in Santa Ana, Cagayan Province; Lal-lo Airport in Cagayan; and Camp Melchor Dela Cruz in Gamu, Isabela.
In a press release, Philippine Defense Minister Carlito Galvez Jr. called the four bases “very strategic,” particularly the naval base at Cagayan and the one on Balabac Island.
The Camilo Osias Naval Base in northern Luzon is just 500 kilometers (310 miles) from Kaohsiung, Taiwan’s third largest city with a population of 2.7 million.
Galvez said Balabac lies on important sea routes in the South China Sea, where Manila and Beijing have competing territorial claims, including over islands where Beijing has built military fortifications.
Collin Koh, a research fellow at Singapore’s S. Rajaratnam School of International Studies, said the bases would play a role in any potential conflict in the region.
“The northern sites are not only geared towards an emergency in Taiwan, they are also useful in times of conflict in the South China Sea,” Koh said. “It’s hard to imagine that a cross-strait conflict will exclude a dimension in the South China Sea.”
Koh identified the Bashi Canal on the northern part of the Luzon Strait, closer to Taiwan, as a critical choke point, either for Chinese naval forces to break out of home waters and enter the open Pacific to attack US military installations on Guam to the east, or that US warships enter the South China Sea.
He also stressed how close the Balabac site is to the controversial Mischief Reef, an atoll on which China has built an artificial island housing military installations.
“The Balabac site allows for intelligence gathering and staging of peacetime air and naval activities in the region, which may put the Mischief Reef under closer scrutiny,” Koh said.
China’s Communist Party claims almost all of the South China Sea as its sovereignty, as does Taiwan — an island democracy of 23.5 million that it has never controlled.
Available in emergencies
Both US and Filipino officials stressed that the four new bases would not see a permanent US military presence – which is not allowed under the EDCA – but would be available to US forces in emergencies.
“This is really about regional preparedness,” Singh said during Monday’s press briefing. “You will see an increase in rotational forces in the region,” she said, adding that the MoD would work in lockstep with Philippine partners to quickly modernize the bases.
The announcement comes as US and Philippine forces prepare to conduct their largest-ever joint military exercise later this month, when an estimated 17,600 troops from the two allies join forces for the Balikatan 23 exercises.
Washington and Manila are bound by a mutual defense treaty signed in 1951 that remains in effect, making it the oldest bilateral treaty alliance in the region for the United States.
CNN’s Hayley Britzky contributed to this report.