The Philippine Navy on Tuesday announced that a military counterintelligence program has neutralized an espionage ring involving four individuals who leaked classified operational data.

Rear Adm. Roy Vincent Trinidad, Navy spokesperson for the West Philippine Sea, said three of the individuals are now under the control of the Armed Forces of the Philippines after cooperating with investigators. A fourth individual, a Navy officer, reportedly refused to cooperate.

The breach was uncovered by the military’s Insider Threat Program, which was launched following the implementation of the government’s new Comprehensive Archipelagic Defense Posture.

Trinidad said the leaked information included operational data regarding the West Philippine Sea, as well as strategic basing and modernization plans for the Navy. He noted, however, that the compromise was limited to information categorized as “classified,” the lowest level of security clearance, below “confidential,” “secret” and “top secret.”

“Their access level was to classified information,” Trinidad said, adding that the leaks did not compromise the country’s primary objectives in the South China Sea, specifically at Ayungin Shoal.

Trinidad credited the success of the operation to the military’s internal monitoring systems but called for new legislation to provide better tools for addressing such threats.

“The internal threat program is working, as manifested by these accomplishments,” Trinidad said. “It is continually being evaluated and enhanced.”

The military declined to provide further details on the suspects or any ongoing operations related to the case, citing the sensitive nature of the investigation.