SECRETARY of National Defense Gilberto C. Teodoro, Jr. and Lithuanian Minister for National Defense Dovilė Šakalienė signed a Memorandum of Understanding on Defense Cooperation on June 30, 2025, in Makati City. — DEPARTMENT OF NATIONAL DEFENSE

MILITARY LEADERS are working to enforce a “one-theater” concept in both the East and South China seas, the Philippines’ defense minister said on Monday, adding that the Southeast Asian country faces threats in disputed waters that are similar to Japan’s.

Japanese newspaper Asahi reported in April that Japanese Defense Minister Gen Nakatani made a proposal to US Pentagon Secretary Pete Hegseth to consider the East China Sea, the South China Sea, the Korean Peninsula and surrounding areas as a single “theater,” referring to a military area of operation.

Philippine Defense Secretary Gilberto C. Teodoro, Jr. said it was “reasonable” to treat both the East and South China seas as a single area of operation, saying both are maritime areas with no land borders involved. However, he said the area should exclude the Korean Peninsula.

“That will involve synergy in operations, synergy in domain awareness, in intelligence exchange, and in mutually reinforcing our strengths to work doubly real-time,” he said at a briefing during the visit of his Lithuanian counterpart Dovilė Šakalienė.

Japan and China have repeatedly faced off over uninhabited Japanese-administered islands in the East China Sea that Tokyo calls the Senkaku and Beijing calls the Diaoyu.

The Philippines and China, meanwhile, have clashed frequently in the South China Sea around disputed shoals and atolls that fall inside Manila’s exclusive economic zone.

China’s embassy in Manila did not immediately respond to a request for comment.

Japan’s Joint Operations Command is operationalizing the single-theater concept, and the “Squad” grouping that includes the defense ministers of Australia, Japan, the Philippines and the United States will establish a coordinating center in December to enforce it, Mr. Teodoro said.

“So, it is already an operating concept. It does not need any other agreement,” Mr. Teodoro said.

Japan and the Philippines last year signed a military agreement that could allow their soldiers on each other’s soil.

Under President Ferdinand R. Marcos, Jr., the Philippines has extended its arc of alliances beyond the United States, its traditional ally, signing defense deals with Japan and New Zealand, and negotiating for similar agreements with Canada and France.

PHL-LITHUANIA MOU
On Monday, the Philippines and Lithuania signed a memorandum of understanding (MoU) to deepen defense cooperation in areas like cyber security, maritime security and munitions production.

“The interesting thing is that we’re facing absolutely similar threats, and our hostile neighbors are using absolutely similar approach,” Lithuanian Defense Minister Šakalienė said in the joint briefing with Teodoro.

The MoU on defense cooperation is expected to bolster their security ties by providing a framework for possible defense industry partnership and maritime security activities.

“This MoU is not symbolic,” Ms. Šakalienė said in her opening remarks, according to a transcript from the Defense department.

“It’s a framework for meaningful cooperation, and we are really hoping that it will develop to a final plan that will provide us with a framework for further cooperation.”

The Philippine and Lithuanian defense chiefs earlier met at a top-level security forum in Singapore last month, where they both committed to upholding international law and countering “unilateral actions” that threaten regional stability, the Defense department said in a statement.

“We see great potential for cooperation with the Philippines in many areas such as maritime security, including challenges related to shadow fleets by some big countries,” said Ms. Šakalienė.

The MoU is a “groundbreaking” development as formalizes avenues for “closer” cooperation on various defense concerns, Mr. Teodoro said in a media briefing.

“Both of us agreed that we need to work together cross-regionally for several important things… [such as] the need to resist any unilateral attempts to reword or re-engineer maritime law and the international order to the benefit of new powers that want to dominate the world,” he said.

China claims nearly all of the South China Sea via a U-shaped, 1940s nine-dash line map that overlaps with the exclusive waters of the Philippines, resulting in clashes at disputed maritime features, as both the countries uphold their claims in the marine-rich water.

A United Nations-backed tribunal in 2016 voided China’s sweeping claims for being illegal, a ruling that Beijing does not recognize. — Kenneth Christiane L. Basilio with Reuters