The US-Philippine alliance sees signs of tightening. (Photo: ABCNews)

The sites are the Camilo Osias navy base in Sta Ana and Lal-lo airport, both in Cagayan province, Camp Melchor Dela Cruz in Gamu, Isabela province, and the island of Balabac off Palawan.

These locations are considered to be strategically important. The office of the Philippine President said the additional sites will boost disaster response and humanitarian and relief operations.

Earlier, the Chinese embassy in Manila it criticized the EDCA, calling it part of the US’s efforts to encircle and contain China through its military alliance with the Philippines.