Just hours after his inauguration on June 30, 2016, Philippine President Rodrigo Duterte nonchalantly declared that he would not "taunt" China with the landmark international ruling supporting his country's arbitration case on the South China Sea. It was a remarkable climbdown for the leader of a country that for years had been at the forefront of diplomatic efforts to constrain Chinese maritime assertiveness in regional waters.

Duterte's predecessor, Benigno Aquino III, who filed the arbitration case, often likened China to Nazi Germany, welcomed the rise of Japan as a "normal" military power and was an enthusiastic supporter of America's "pivot to Asia" policy. In contrast, Duterte has tried to distance the Philippines from the U.S. in response to festering disagreements over human rights concerns, while viewing China as a partner in national development.

By the end of last year, Duterte said he would "set aside" entirely the arbitration ruling in order to improve relations with China. The Filipino leader also made it clear that he would not raise the arbitration case in regional gatherings, particularly within the Association of Southeast Asian Nations. Few regional observers therefore expected much discussion of the ruling during the Philippine's chairmanship of ASEAN this year.

But what has caught many by surprise has been Duterte's avoidance of any mention of China's massive reclamation activities in the South China Sea, primarily its moves to create a sprawling network of military facilities that have rattled neighboring countries as well as the U.S.

The recent joint statement on the South China Sea dispute issued at the ASEAN summit on April 29 ended up being even softer than those over the previous three years, including one at the 2016 ASEAN summit chaired by Laos, which is seen as a key Chinese proxy in the region. Duterte's blatant acquiescence to China has upset senior Filipino officials, among others in the region.

An exasperated Filipino diplomat lamented how his country has ended up "being lumped together with Cambodia and Laos in protecting Chinese interests [in ASEAN] at all costs." Initially, there had been some hope that Duterte would leverage his chairmanship of ASEAN to push back against China.

Mixed signals

Observers pointed to the fact that the Philippines promised to finalize a framework for a legally-binding "code of conduct" in the South China Sea before the end of the year. During the ASEAN foreign ministers meeting in February, former Philippine Foreign Secretary Perfecto Yasay ruffled Chinese feathers by stating that several member states had raised Manila's arbitration case as a possible reference for managing the South China Sea disputes.

In recent weeks, senior Filipino defense officials, especially Defense Secretary Delfin Lorenzana, openly accused China of threatening his country's sovereign rights and territorial integrity. After Duterte initially promised to plant the Philippine flag on the disputed island of Thitu, a controversial statement which he later retracted, he dispatched Lorenzana as well as his military Chief of Staff Eduardo Ano to disputed land features in the Spratly chain of islands.

Duterte also allocated 1.6 billion pesos ($32 million) for the refurbishment and upgrading of Philippine civilian and military facilities on land features in the South China Sea that are under Manila's administration, including the airstrip on Thitu. In response, Beijing said it was "gravely concerned" and "dissatisfied" with the action and warned against any disruption in the "hard-won, sound momentum" in bilateral relations under Duterte.

Yet, all hopes were dashed when Duterte made it clear that he was not interested in alienating China by taking a tough position as ASEAN chairman. Without question, Duterte's soft position was welcomed by some regional states, particularly Laos, Cambodia and Brunei, which have prioritized economic relations with China over regional disputes.

According to those familiar with the behind-the-scenes negotiations on the drafting of the ASEAN statement, Duterte reportedly vetoed efforts by some claimant states, particularly Vietnam, to mention the Chinese reclamation activities.

"Your president has defined the outcome...already," a visibly frustrated Southeast Asian diplomat told a Filipino TV news channel. "Some are frustrated over the turn of events." Other ASEAN states, particularly Indonesia, Malaysia and Singapore, are also worried about China's growing military presence in the area.

Singapore, which has consistently urged all claimant states to respect international law and the arbitration ruling, has increased military cooperation with the U.S., which enjoys long-term access to the city-state's Changi port. Meanwhile, Kuala Lumpur is quietly building up its military presence close to disputed land features in the South China Sea as China expands its coast guard and fishing activities within Malaysia's Exclusive Economic Zone.

Last year, Malaysian diplomats tried to advocate tougher language on the Chinese-led militarization during the ASEAN-China foreign ministers meeting in Kunming, China. But those efforts were reportedly blocked by Cambodia and Laos.

Even the Indonesian President Joko Widodo, who is known for his focus on trade and investments rather than sensitive geopolitical issues, openly advocated for a more robust and unified ASEAN stance during the recent summit. "South China Sea is one of the issues that we need to solve immediately," Jokowi said. "I think we need to have a common stand."

Although not a claimant state, Indonesia has been increasingly open about its concerns over China's military and fishing presence in Indonesia waters, particularly those close to the energy-rich Natuna islands. As a result, Jakarta has not only expanded military activity in Indonesian waters, but has also adopted a "sink boat" policy against foreign vessels illegally fishing there.

Domestic agendas

Instead of focusing on the South China Sea disputes, Duterte used the chairmanship of ASEAN to defend his brutal campaign against illegal drugs, which has come under heavy criticism by Western countries and international organizations, including the United Nations. He called on the European Union and the U.S. to refrain from interfering in the domestic affairs of ASEAN members, a statement that struck a chord among the region's autocratic leaders.

Duterte's soft-pedaling of the South China Sea issue was likely a calculated move ahead of his upcoming meeting with Chinese President Xi Jinping on the sidelines of the summit on the Belt and Road Initiative in Beijing in mid-May.

In exchange for easing ASEAN pressure on China, the Filipino leader will likely seek economic concessions, particularly infrastructure investment in Duterte's home island of Mindanao, and a modus vivendi in disputed waters, such as around the Spratlys and Scarborough Shoal, both claimed by Manila.

As part of a bilateral bargain, Duterte could ask China to stop building structures on Scarborough Shoal as well as allow Philippine surveillance operations, resupply routes and fishing activities in the disputed waters.

But by adopting a conciliatory stance, Duterte's transactional approach runs the risk of emboldening greater Chinese assertiveness. This could hasten ASEAN's demise and slide into strategic irrelevance. ASEAN, which is celebrating its 50th anniversary this year, is more internally divided than ever as member states pursue their national interests at the expense of deeper regional integration.

Richard Heydarian is a Manila-based academic, columnist and author of "Asia's New Battlefield: US, China and the Struggle for the Western Pacific."