If you ask policymakers in Washington or Tokyo about trilateral cooperation in Asia, most will talk about the importance of the hard-won partnership between the United States, Japan, and South Korea. But out of the limelight, the “other trilat” is becoming a uniquely formidable partnership. Launched at a 2023 meeting of the three countries’ national security advisors, the U.S.-Philippines-Japan trilateral partnership seized on Japan’s growing sense of responsibility for regional security, unprecedented momentum in the U.S.-Philippines alliance, and a common belief that the region’s most pressing challenges could be solved only through collaboration among like-minded countries.

In June, Coast Guard ships hailing from the United States, the Philippines, and Japan undertook joint operations near Japan’s Kagoshima prefecture, on the cusp of the East China Sea. At a time when China is wielding its own Coast Guard to bully neighbors and craft a new regional order defined by deference to Beijing, the multinational fleet sailing through Kagoshima Bay sent a powerful signal of resolve that would have been difficult to imagine just a few years earlier.

In June, Coast Guard ships hailing from the United States, the Philippines, and Japan undertook joint operations near Japan’s Kagoshima prefecture, on the cusp of the East China Sea. At a time when China is wielding its own Coast Guard to bully neighbors and craft a new regional order defined by deference to Beijing, the multinational fleet sailing through Kagoshima Bay sent a powerful signal of resolve that would have been difficult to imagine just a few years earlier.

If you ask policymakers in Washington or Tokyo about trilateral cooperation in Asia, most will talk about the importance of the hard-won partnership between the United States, Japan, and South Korea. But out of the limelight, the “other trilat” is becoming a uniquely formidable partnership. Launched at a 2023 meeting of the three countries’ national security advisors, the U.S.-Philippines-Japan trilateral part