“I announce my separation from the United States,” the tough-talking Philippine president Rodrigo Duterte declared during his first state visit to China. Two years later, the Philippines has formally called for a formal review of its decades-old alliance with the US. Philippine Defence Secretary Delfin Lorenzana, formerly a long-time Washington defence attaché, made it clear that Manila isn’t ruling out the abrogation of the 1951 US-Philippine Mutual Defence Treaty. While the review could serve as a springboard for fine-tuning the alliance, which has been hobbled by disagreements and commitment issues in recent years, it’s ultimately a double-edged sword. After all, proponents of warmer ties with Beijing could very well lobby for downgrading the Philippine-US alliance in favour of strategic neutrality, especially if both parties failed to agree on the necessary upgrades. The call for review was met by shock and disbelief among many observers, who expected an immediate and sustained thaw in bilateral relations after Washington returned the famed Balangiga Bells to the Philippines. Duterte warmly welcomed the return of the historical artefacts, which were taken by American forces from a Philippine church during the colonial period, as a necessary closure to a dark chapter in the countries’ shared history. South China Sea clash is biggest worry for Philippine firms There was even a hope that Duterte, who has already made three official visits to China, would finally entertain the White House’s long-standing invitation for a state visit. Instead, it seems even the Philippine defence establishment, which has been the bedrock of the bilateral alliance, is showing growing frustration over American strategic ambivalence. The Philippine defence chief openly lamented Washington’s “ambivalent” position on the exact coordinates of its commitments to the Philippines, especially in light of the South China Sea disputes. He explicitly questioned whether the Mutual Defence Treaty is “still relevant to our security” instead of just serving “the interest of other nations”, namely the US. The first problem with the alliance is the very text of the treaty. According to Article V of the MDT, “an armed attack on either of the Parties is deemed to include an armed attack on the metropolitan territory of either of the Parties, or on the island territories under its jurisdiction in the Pacific or on its armed forces, public vessels or aircraft in the Pacific.” Yet, Washington has equivocated on what exactly it considers to be part of “metropolitan” Philippines and the “island territories under its jurisdiction”. Aquino slams SCS resource-sharing deal with Beijing To the Philippines’ horror, its ally largely stood by when China occupied Philippine-claimed Mischief Reef in 1994 as well as during the months-long Philippine-China naval stand-off over the Scarborough Shoal in 2012. The US has repeatedly refused to clarify whether its treaty commitments apply in the South China Sea, where the Philippines is at loggerheads with several other claimant states. Moreover, there are doubts whether the treaty provides expedient military help in the event of conflict between the Philippines and any hostile third party. According to Article IV of the treaty, each party “would act to meet the common dangers [in their area of jurisdiction] in accordance with its constitutional processes”. Manila worries whether it could rely on American military support if China or other rival claimant states were to directly threaten its supply lines and military personnel Operationally, this means the US Congress, and American public opinion by extension, could delay and deny efforts by any US administration to urgently intervene on behalf of its Philippine ally during an armed contingency. Adding insult to injury, Washington has made it clear that its 1951 US-Japan Security Treaty, for instance, applies to the disputed Senkaku/Diaoyu Islands in the East China Sea. The US-Japan mutual defence treaty also makes it clear that American forces stationed in Japan “may be utilised to contribute … to the security of Japan against armed attack from without”. The other major problem lies in America’s narrow interpretation of the MDT. Beginning with the Nixon administration in the 1970s, Washington has limited its commitments to any “attack on [Philippine] forces deployed to third countries”, but not in situations “where deployment is for the purpose of enlarging Philippine territory”. The US maintains official “neutrality” over the sovereignty status of disputed islands in the South China Sea, where the Philippines occupies nine land features. Manila worries whether it could rely on American military support if China or other rival claimant states were to directly threaten its supply lines and military personnel stationed in the area. By calling for a formal review, the Philippine defence establishment likely hopes to compel the US to revisit both the text and its interpretation of the MDT in ways that are more mutually satisfactory. In exchange, Manila may grant US troops expanded access to its military bases, particularly the Bautista and Basa airbases bordering the South China Sea. The review process, however, also opens the space for critics as well as proponents of warmer ties with China to call on the Philippines to adopt an official policy of strategic neutrality and, accordingly, downgrade the Philippine-US bilateral alliance. Philippine defence chief urges review of security treaty with US This is likely to be the case if Washington stubbornly holds onto its policy of strategic ambiguity over its commitments to the Philippines in the South China Sea. Three years into Duterte’s presidency, the Philippine-US alliance is reaching a historic crossroads. Richard Heydarian is a Manila-based academic and author