In the turbulence of global politics over the last year, Vietnam has been no stranger to great political shocks. U.S. president Donald Trump’s abrupt about-face on the Trans-Pacific Partnership agreement (TPP) left leadership and reformers in Hanoi alike fighting to regain lost momentum in the push to restructure and upgrade their nascent capitalist economy while also addressing their heavily lopsided trade linkages with China. The Trump administration’s early overtures to China also raised the specter of a “grand bargain” between the two superpowers at the expense of smaller nations. Many, including Vietnam, have feared that Trump may seek to renegotiate terms of trade with China as well as solicit the Asian giant’s assistance on North Korea in exchange for a modus vivendi in Beijing’s backyard.

The ascent of Philippine president Rodrigo Duterte, however, has come as a political shock to Vietnam that has not received its due in media coverage. Since the beginning of his presidency in June 2016, the Filipino leader has not only downgraded his country’s strategic cooperation with the United States, but has also taken a markedly softer stance on China in the South China Sea than his predecessor. As the chairman of the Association of Southeast Asian Nations (ASEAN) this year, Duterte has proactively shielded China from any criticism. As a result, Vietnam has been left to wage a lonely fight against China’s maritime ambitions in the region.

Alliance of Convenience

Just a year ago, the Philippines and Vietnam were considered de facto allies in the South China Sea. As the two countries with the greatest number of land features under their control in the Spratly Islands, Vietnam and the Philippines have the most to lose from China’s expanding military footprint in the contested area.

Between the years 2011 and 2016, the Southeast Asian neighbors gradually gravitated towards one another. Perturbed by China’s rising assertiveness in the South China Sea, they began to put aside ideological differences and decades of mutual suspicion in favor of tactical cooperation.

In 2014, Vietnam made the unprecedented move of dispatching its most powerful warships, two Russian-built missile-guided frigates, for a high-profile goodwill visit to the Philippines. Lieutenant Commander Marineth Domingo of the Philippines welcomed Vietnam’s “first port call” as a “a positive and good sign of the improving and deepening relations between the Philippine Navy and Vietnam People’s Navy.”

Beijing fired back with marked concern, as Foreign Ministry spokeswoman Hua Chunying urged “all sides [to] do more to increase mutual trust and safeguard regional peace and stability.” It was a thinly-veiled shot against the burgeoning military cooperation between the two countries.

That year also saw Filipino and Vietnamese troops enthusiastically playing volleyball and sharing beer on Southwest Cay. The disputed island was occupied by the Philippines until 1975, when South Vietnamese troops wrested control of the island out from under the noses of Filipino troops temporarily visiting nearby Northeast Cay for a party.

For decades, the incident left a deeply negative impression of Vietnam on Filipinos, who began to view Hanoi—successor to South Vietnam’s holdings in the South China Sea—as an opportunistic and untrustworthy rival. Hanoi controls by far the most features in the Spratlys and surrounding area (27), followed by the Philippines (8) and then China (7).

Despite those suspicions, the two countries saw value in closer cooperation as Chinese power continued to grow. Vietnam supported, albeit surreptitiously, the Philippines’ landmark arbitration case against China in the South China Sea. Although it declined to file a parallel case, Hanoi discussed the possibility of seeking Manila’s legal assistance if and when it chooses to pursue a similar course of action. Crucially, the two neighbors signed a strategic partnership agreement in 2015 amid much fanfare. The pact paved the way for more regularized defense, strategic and economic cooperation.

The Duterte Shock

But with the rise of Duterte, what looked like a burgeoning strategic alliance rapidly turned into a lukewarm, bordering on tense, relationship. Just one month into office, the new Filipino president effectively set aside the legal warfare strategy of his predecessor, Benigno Aquino III, in favor of engagement with China.

Moreover, the Filipino president scaled back joint military exercises with the United States in the South China Sea, including plans for joint patrols in waters disputed with China. This provided China with greater room to operate in disputed waters at the expense of Vietnam, which hastily responded with fortifications of its island holdings.

Duterte did at first send encouraging signals to Vietnam, especially when he visited Hanoi in his first few months in office and called for greater cooperation among ASEAN countries. Shortly after, as a gesture of good will, he even released 17 Vietnamese fishermen who had been jailed for illegally fishing in Philippine waters.

In recent months, however, tensions have flared up between the neighbors, especially after a Philippine Navy warship fired on several Vietnamese fishermen, killing two of them. The Duterte administration promised impartial and thorough investigations, but the episode has highlighted an increasingly tepid relationship between two former strategic partners.

During ASEAN meetings this year, Vietnam and the Philippines have repeatedly butted heads over disagreements on the need to confront China over its reclamation activities in the South China Sea. Vietnam has, often unsuccessfully, insisted on a tougher stance against China, but faced resistance from the Philippines in its role as the regional body’s chairman.

In a subtle criticism of Vietnam, Philippine foreign secretary Alan Peter Cayetano has often pointed fingers at ASEAN countries (specifically Vietnam) for engaging in reclamation activities in the South China Sea, while falsely claiming that China has ceased those activities in recent months.

Influential commentators in the Philippine media have begun complaining about increasing numbers of Vietnamese fishermen encroaching on Philippine waters, while others have begun to openly portray Hanoi as the main threat in the Spratly chain of islands. As the Philippines warms up to China and the Trump administration wavers in its commitment to constrain Beijing’s maritime ambitions, Vietnam has found itself in an unenviable strategic solitude. It marks a dramatic strategic turn of events in the ongoing South China Sea saga.

About Richard Javad Heydarian

Richard Javad Heydarian is an assistant professor in political science at De La Salle University, and a policy adviser at the Philippine House of Representatives (2009-2015). He is the author of Asia’s New Battlefield: The US, China, and the Struggle for Western Pacific.