One site is near the hotly disputed South China Sea and another not far from Taiwan.
The office of Philippine President Ferdinand Marcos Jr has named the four additional bases that United States forces will have access to under an existing defence agreement to expand military cooperation.
The Philippine government announced in February that it would allow rotating batches of US forces to indefinitely stay in the new camps, in addition to five local bases earlier designated under a 2014 Enhanced Defence Cooperation Agreement (EDCA).
The locations of the additional bases, however, 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 in Isabela and Cagayan, on the island of Luzon, 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 cited by AFP news agency confirmed that the locations announced by the palace were the new EDCA sites.
The expansion comes as China becomes increasingly assertive in pressing its claim to the self-ruled island of Taiwan, as well as in the South China Sea, where it claims almost the entire waterway under its controversial nine-dash line. The Philippines, other Southeast Asian nations and Taiwan also have overlapping claims to the sea, which is a major global trade route.
Cagayan Governor Manuel Mamba has publicly opposed having EDCA sites in his province for fear of jeopardising Chinese investment and becoming a target in a conflict over Taiwan.
But Philippine acting defence chief Carlito Galvez told reporters recently that the government had “already decided” on the sites and that Mamba had agreed to “abide with the decision”.
The agreement allows US troops to rotate through the bases and also store defence equipment and supplies at them.
The EDCA stalled under former President Rodrigo Duterte, who favoured China and threatened to sever ties with the US and expel its troops.
But ties have warmed up under the administration of Marcos Jr, who has sought to accelerate the pact’s implementation after taking office in June last year and adopting a more US-friendly foreign policy.
China has been critical of the agreement, which its embassy in the Philippines said recently was part of “US efforts to encircle and contain China through its military alliance with this country”.
Al Jazeera and news agencies