The U.S. Department of Defense plans to open four new military sites in the Philippines for "regional readiness," as part of the Enhanced Defense Cooperation Agreement, or EDCA, which went into effect on Feb. 1.

Deputy Pentagon Press Secretary Sabrina Singh said during a press conference on Monday that the new sites would be located at Naval Base Camilo Osias in Santa Ana, Cagayan; Camp Melchor Dela Cruz in Gamu, Isabela; Balabac Island in Palawan; and Lal-lo Airport in Cagayan.

USS Milius DDG69 is seen in 2012

A general view shows the USS Milius DDG69, a multi-mission capable guided missile destroyer ship docked at the Manila south harbor on Aug. 18, 2012. (NOEL CELIS/AFP/Getty Images)

"In addition to the five existing sites, these new locations will strengthen the interoperability of the United States and Philippine armed forces and allow us to respond more seamlessly together to address a range of shared challenges in the Indo-Pacific region, including natural and humanitarian disasters," she said. "The Department of Defense will work in lockstep with the Philippine Department of National Defense and Armed Forces to rapidly pursue modernized Asian products at these locations."

US, PHILIPPINES ANNOUNCE NEW AGREEMENT TO RAMPU UP MILITARY PRESENCE AMID CHINA-TAIWAN TENSIONS

Singh said one of the locations is an airport expansion, adding that some of the sites would be used for training, particularly with the U.S. Navy.

She would not comment on how many troops would be sent to the Philippines, nor when the Department of Defense would begin sending troops there, saying she did not have the numbers on her during the press briefing.

Philippines US Military

Members of US marines guards fold their national flag during the closing ceremony of the annual joint US-Philippines military exercise in Manila on May 19, 2017.  ((Photo credit should read TED ALJIBE/AFP via Getty Images))

In February, the U.S. announced its intentions to ramp up its military presence in the Philippines, amid growing tensions between China and the island of Taiwan.

DEFENSE SECRETARY AUSTIN 'SERIOUSLY DOUBTS' CHINA INVASION OF TAIWAN IS 'IMMINENT'

The Philippines is the U.S.’s oldest treaty ally in Asia and used to host two of the largest U.S. Navy and Air Force bases outside the American mainland. The bases were shut down in the early 1990s.

The Philippine Constitution prohibits the permanent basing of foreign troops, but the EDCA defense pact allows visiting American forces to indefinitely stay in rotating batches within designated Philippine camps. The agreement makes allowances for defense equipment but does not allow nuclear weapons.

Lawrence Richard of Fox News contributed to this report.

CLICK HERE TO GET THE FOX NEWS APP