Four new military bases will be established in the Philippines as part of the Expanded Defense Cooperation Agreement (EDCA) with the United States, according to President Ferdinand Marcos Jr. on Wednesday. One of the sites will be in a province that faces the South China Sea.

With China’s escalating aggression in the South China Sea and toward self-ruled Taiwan, Marcos allowed the United States access to four additional sites last month in addition to the five already authorized under the 2014 EDCA.

“There are four extra sites scattered around the Philippines – there are some in the north, there are some around Palawan, there are some further south,” Marcos told reporters at the sidelines of the Philippine army’s founding anniversary.

EDCA allows U.S. access to Philippine bases for joint training, pre-positioning of equipment and building of facilities such as runways, fuel storage and military housing, but it is not a permanent presence.

The Philippines and the United States would announce the locations of the bases soon, Marcos said, adding the sites would boost the country’s ability to defend the “eastern side” of its largest island, Luzon. Luzon is the closest main Philippine island to Taiwan.

A former Philippine military chief has publicly said the United States had asked for access to bases in Isabela, Zambales and Cagayan, all on the island of Luzon, facing north towards Taiwan, and on Palawan in the southwest, near the disputed Spratly Islands in the South China Sea.

Some leaders of local governments at the potential EDCA sites have opposed Marcos’ decision, worried they would be dragged into a conflict if one arose between the United States and China over Taiwan.

But Marcos said his government has discussed with them the importance of the expanded U.S. access and “why it will actually be good for their provinces.”

Washington has committed $80 million worth of infrastructure investments at the five existing sites – the Antonio Bautista Air Base in Palawan, Basa Air Base in Pampanga, Fort Magsaysay in Nueva Ecija, Benito Ebuen Air Base in Cebu and Lumbia Air Base in Mindanao.

Speaking before Philippine troops, Marcos told them to be vigilant as the external threat to his country’s security was becoming more “complex” and “unpredictable.”

“Be vigilant against elements that will undermine our hard earned peace, our hard earned stability, continue to improve relations with your counterparts overseas,” Marcos said.

Without giving specifics, Marcos said he was aware of an “emerging threat” to his country’s territory, which he said would require “adjustments in our strategy.”

“The external security environment is becoming more complex. It is becoming more unpredictable,” Marcos said.