The 1951 Mutual Defense Treaty (MDT) between the Philippines and the United States has been a cornerstone of Philippine security policy for over seven decades.

However, recent geopolitical developments, particularly the ongoing tensions in the West Philippine Sea (WPS), have sparked calls for a review of this treaty. Senator Imee Marcos, among other voices, has suggested re-evaluating the treaty to ensure it remains relevant in today’s complex security environment.

The Mutual Defense Treaty was established during the early Cold War period, primarily to counter the spread of communism in Southeast Asia. It commits both nations to support each other in the event of an external attack. For decades, this treaty has been the bedrock of the Philippines’ defense strategy, providing a security umbrella under which the country has developed.

However, the strategic landscape of the 21st century differs markedly from that of the early 1950s.

The rise of China as a regional power and its increasingly assertive actions in the WPS pose new challenges that the original treaty may not fully address. Beijing’s militarization of disputed areas, frequent incursions into Philippine waters, and its broader geopolitical ambitions necessitate a fresh look at the defense agreement to ensure it adequately protects Philippine interests.

The MDT, while a strong symbol of bilateral cooperation, contains ambiguities regarding its application in the South China Sea. The treaty’s language commits both nations to mutual defense in the event of an “armed attack,” but it is unclear if this includes non-traditional forms of aggression such as cyber-attacks or gray zone tactics now commonly employed by China. A review could help clarify these points, ensuring a robust and precise understanding of the treaty’s provisions.

Since the treaty was signed, the nature of warfare and defense technology has evolved significantly. A review could facilitate the inclusion of contemporary security challenges such as cyber warfare, terrorism, and maritime security. Enhancing joint training exercises, intelligence sharing, and technology transfer would better prepare both nations to face current and future threats.

A more explicit and updated treaty could serve as a stronger deterrent against Chinese aggression. If Beijing perceives that the US commitment to defend the Philippines is unequivocal and includes responses to various forms of aggression, it might think twice before engaging in provocative actions in the WPS.

A comprehensive review of the MDT can reassure other Southeast Asian nations of the US’s commitment to regional security. This can foster greater cooperation among ASEAN countries and strengthen collective security arrangements in the face of China’s assertiveness.

A review of the MDT, however, might be seen as a provocative act by China, potentially escalating tensions further. Beijing could interpret the move as an attempt to strengthen US influence in the region, prompting more aggressive actions in the WPS.

The review process, likewise, might deepen domestic political divisions within the Philippines. Different political factions have varying views on the country’s relationship with the US, and a treaty review might become a contentious issue, distracting from other critical governance issues.

While the US is likely to support a review to reaffirm its commitment, the negotiation process might strain diplomatic relations if disagreements arise over specific terms and conditions. Both nations must navigate this process carefully to avoid any unintended friction.

Looking at the whole picture, the call for a review of the MDT is both prudent and timely given the evolving security landscape in the Asia-Pacific region. While the treaty has served as a vital component of Philippine defense policy, the current geopolitical realities — especially the aggressive posturing of China in the West Philippine Sea — necessitate a thorough reassessment.

Ultimately, a carefully managed review process, aimed at reinforcing the treaty’s relevance and robustness, could significantly enhance the security and stability of the Philippines and the broader region. It is an opportunity to ensure that this long-standing alliance continues to serve the best interests of both nations in an increasingly complex and contested global environment.