One location is near the hotly contested South China Sea and another not far from Taiwan.
The office of Philippine President Ferdinand Marcos Jr. has named the four additional bases that US forces will have access to under an existing defense agreement to expand military cooperation.
The Philippine government announced in February that alternating parties would be allowed to indefinitely allow U.S. troops to remain in the new camps, in addition to five local bases previously designated under a 2014 Enhanced Defense Cooperation Agreement (EDCA).
However, the locations of the additional bases were withheld until Monday while the government consulted with local officials.
The Presidential Communications Office said in a statement that the four sites will be located in Isabela and Cagayan, on Luzon Island, facing north towards Taiwan, and on Palawan, near the disputed Spratly Islands in the South China Sea.
The bases had been assessed by the Philippine military and deemed “suitable and mutually beneficial,” the statement said, noting that the camps would also be used for humanitarian and relief operations during disasters.
A US official quoted by the AFP news agency confirmed that the locations announced by the palace were the new EDCA locations.
The expansion comes as China becomes increasingly assertive in its claim to the self-governing island of Taiwan, as well as the South China Sea, where it claims almost the entire waterway under its controversial nine-dash line. The Philippines, other Southeast Asian countries and Taiwan also have overlapping claims to the sea, an important global trade route.
Cagayan Governor Manuel Mamba has publicly opposed having EDCA sites in his province for fear of jeopardizing Chinese investment and becoming a target in conflict over Taiwan.
But Philippine acting defense chief Carlito Galvez recently told reporters that the government had “already made a decision” about the sites and that Mamba had agreed to “commit to the decision.”
The agreement allows US troops to rotate through the bases and also store defense equipment and supplies there.
The EDCA was bogged down under former President Rodrigo Duterte, who favored China and threatened to cut ties with the US and expel its troops.
But ties have warmed under the administration of Marcos Jr., who, after taking office last June, has sought to accelerate implementation of the pact and adopted a more US-friendly foreign policy.
China has criticized the deal, which its embassy in the Philippines said recently formed part of “US efforts to encircle and contain China through its military alliance with this country.”