The leaders of the United States, Japan and the Philippines on Thursday agreed to advance their defense and economic cooperation, in a move aimed at pushing back against China's ambitions in the Indo-Pacific region.

U.S. President Joe Biden, Japanese Prime Minister Fumio Kishida and Philippine President Ferdinand Marcos Jr. expressed "serious concerns" about China's "dangerous and aggressive" actions in the South China Sea in a statement released after the first-ever summit between leaders of the three countries, held in Washington.

Major initiatives agreed upon at the White House include supporting Philippine defense modernization efforts and a plan to conduct a joint maritime exercise of naval forces around Japan in 2025.

The United States and Japan will also further assist the Philippine Coast Guard to strengthen its capabilities, with the three announcing the establishment of a trilateral maritime dialogue to improve coordination.

Philippine President Ferdinand Marcos Jr. (L), U.S. President Joe Biden (C) and Japanese Prime Minister Fumio Kishida meet for a summit at the White House in Washington on April 11, 2024. (Kyodo)

As part of steps to enhance interoperability, a U.S. Coast Guard vessel will welcome Japanese and Philippine coast guard members aboard during a patrol this year.

Apart from promoting such drills and combined naval training, they agreed to launch a trilateral humanitarian and disaster response exercise involving their navies.

As they began discussions, Biden said he wanted to be clear that U.S. defense commitments to Japan, which faces confrontational Chinese maneuvers over the Senkaku Islands in the East China Sea, and the Philippines are "ironclad."

The summit was held a day after Biden hosted Kishida for an official meeting and a lavish state dinner, during which the two voiced their resolve to deepen ties with like-minded countries to ensure peace and stability in the region and beyond.

While calling their talks "historic," Marcos said, "But this meeting can be just a beginning. Facing the complex challenges of our time requires concerted efforts on everyone's part."

Kishida said that "multi-layered cooperation between allies and like-minded countries is essential if we are to maintain and bolster a free and open international order based on the rule of law."

At a time when the Philippines is under increased pressure from China over the Second Thomas Shoal in the disputed South China Sea, the leaders underscored their staunch commitment to respecting international law and the sovereign rights of other states.

Biden reiterated that any attack on Philippine aircraft, vessels or armed forces in the South China Sea will invoke their long-standing defense treaty, which obliges each to assist the other if it comes under attack.

The three-way meeting was held as the United States and Japan seek to increase joint defense exercises with Australia, Britain and the Philippines.

The Marcos administration is struggling to combat Chinese activity in contested areas of the South China Sea, while at the same time being wary of the possibility it could be dragged into the geopolitical rivalry between Washington and Beijing.

Last month, vessels from China, which claims sovereignty over almost the entire South China Sea, once again hit a Philippine boat with water cannons near the Manila-controlled shoal, damaging the vessel and injuring its navy crew members.

In addition to boosting cooperation on maritime safety, the leaders expanded the scope of the trilateral framework to economic projects in the Philippines linked to infrastructure, supply chains and energy.

One of the main projects is to support the development of an economic corridor on the most populous Philippine island of Luzon.

The development is aimed at improving connectivity between Subic Bay, Clark, Manila and Batangas, with "high-impact infrastructure projects" expected, including the modernization of ports and railways.

The two countries will also support the Philippines' access to cutting-edge technologies, such as those related to semiconductors and wireless communication systems, and on the transition to cleaner energy, offering more training for policymakers, scientists and engineers on nuclear energy.

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