In commentaries tackling the treaty alliances of the United States, Thailand has often been referenced as its oldest Asian ally. Yet, some would also address the Philippines as the US oldest ally in Asia, so one—like myself—would be left confused. So, which of which is truly the oldest ally? Of course, it can’t be both unless they’ve forged an alliance simultaneously, right?

So, which of the two Southeast Asian countries is the oldest ally?

We’ll not be delving deep into the relationship history between US-Thailand and US-Philippines—especially with this one, which had a rather complicated history—But rather a brief discussion on what led these two Asian countries to vie for the “oldest” title.

Deep and Enduring

The diplomatic relationship between the US and Thailand was initially cemented around the mid-19th century, predominantly engaging in trading and commerce, and even reached a level of comfort that by the early twentieth century, Americans served the King of Thailand as foreign affairs advisers. They formalized this relationship with a Treaty of Amity and Commerce signed in 1833, the first-ever known American treaty to any Asian country. In 1954, both reaffirmed their alliance with the Manila Pact of the Southeast Asia Treaty Organization (SEATO). Though the treaty was dissolved in 1977, the Manila Pact continued to be enforced, along with other bilateral understandings like the Thanat-Rusk communique of 1962.

“The United States looks forward to strengthening the excellent cooperation between our two countries, as allies and friends. Next year marks 190 years of diplomatic relations.”

Then, in 2003, the US designated Thailand a major non-NATO ally with the 2012 and 2020 Joint Vision Statement, serving as the former’s security commitment to the latter.

Cobra Gold 19 Communications Class
Royal Thai Armed Forces Master Sgt. 1st Class. Puvadon Pumjine, left, assists US Army Pfc. Tyler Standen with Charlie Company, 5th Battalion, 20th Infantry Regiment, in constructing an antenna during a communications class as part of exercise Cobra Gold 19 at Phitsanulok, Kingdom of Thailand, Feb. 15, 2019. (US Marine Corps photo by Cpl. Robert G. Gavaldon)

Moreover, according to the WSJ, the US-Thailand forces frequently engage annually, including military exercises. They have collaborated closely, as well, in law enforcement. The Royal Thai Police and the US Drug Enforcement Agency have worked hand-in-hand against narcotics trafficking since 1963. Not to mention the strategic location of Thailand, positioned in the middle of the ASEAN—the heart of the Indo-Pacific Strategy of the US. Hence, for the latter to maintain its relationship with its long-standing ally not just make sense but is imperative.

Bittersweet Relations

The US and the Philippines have a long, complicated history after the former inherited the latter from the Spanish regime. But, bitter history aside, both countries have long-standing relations involving a broad range of areas of strategic security as well as political, developmental assistance, and economic cooperation. This relation has been brought together because of the Mutual Defense Treaty signed in 1951, making “the Philippines the oldest security ally of the US in Southeast Asia and among the five treaty allies of the US in the Pacific region, similar to the agreements signed by South Korea, Japan, and Europe’s NATO.”