SINGAPORE -- Even by his outspoken standards, Philippine President Rodrigo Duterte’s account of a conversation he had with his Chinese counterpart, Xi Jinping, was startling.

During a meeting between the two leaders in Beijing in May 2017, the subject turned to whether the Philippines would seek to drill for oil in a part of the South China Sea claimed by both countries. Duterte said he was given a blunt warning by China’s president.

“[Xi’s] response to me [was], ‘We’re friends, we don’t want to quarrel with you, we want to maintain the presence of warm relationship, but if you force the issue, we’ll go to war,” Duterte recounted.

A year later, Duterte was asked for a response to news that China had landed long-range bombers on one of the South China Sea's Paracel Islands -- a milestone that suggests the People's Liberation Army Air Force can easily make the short hop to most of Southeast Asia from its new airstrips. “What’s the point of questioning whether the planes there land or not?” Duterte responded.

His refusal to condemn China’s military buildup underlines China's success in subduing its rivals in the South China Sea. Since 2013 China has expanded artificial islands and reefs in the sea and subsequently installed a network of runways, missile launchers, barracks and communications facilities.

These military advances have led many to wonder if Beijing has already established unassailable control over the disputed waters. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have overlapping claims to parts of the South China Sea and its islands – claims that are looking increasingly forlorn in the wake of China’s military buildup.

“What China is winning is de facto control of nearly the entire South China Sea, including all activities and resources in it, despite the other surrounding Southeast Asian states' respective legal rights and entitlements under international law,” said Jay Batongbacal, director of the University of the Philippines Institute for Maritime Affairs and Law of the Sea.

At stake is the huge commercial and military leverage that comes with controlling one of the world’s most important shipping lanes, through which up to $5 trillion worth of trade passes each year.

U.S. Secretary of Defense James Mattis insists that China faces “consequences” for the “militarization” of South China Sea, which he says is being done for “the purposes of intimidation and coercion.”

“There are consequences that will continue to come home to roost, so to speak, with China, if they do not find the way to work more collaboratively with all of the nations,” Mattis said on June 2 at the Shangri-La Dialogue in Singapore, a security conference organized by the London-based International Institute for Strategic Studies.

Mac Thornberry, chairman of the U.S. House Armed Services Committee, added that the U.S. naval presence means China does not have a free hand in the South China Sea.

“I think you will see more and more nations working together to affirm freedom of navigation through the South China Sea and other international waters,” Thornberry told the Nikkei Asian Review.

But what those consequences might be was left unsaid by Mattis, who suggested that there was little prospect of forcing China to give up its growing network of military facilities dotting the sea.

“We all know nobody is ready to invade," he said.

U.S. Defense Secretary James Mattis talked up the "Indo-Pacific" strategy in his June 2 speech at the Shangri-La Dialogue in Singapore. (Photo by Simon Roughneen)

Gregory Poling, director of the Asia Maritime Transparency Initiative at the U.S.-based Center for Strategic and International Studies, said, “There is no reasonable basis for the U.S. to use military force to push China off its outposts, nor would any country in the region support such an effort.”

The U.S. pushback so far has included disinviting China from a major Pacific naval exercise. It also continues to carry out so-called freedom of navigation operations, or FONOPs, the most recent of which took place on May 27. This was followed by U.S. military aircraft flying over the Paracel Islands in early June, a move that prompted a countercharge of “militarization'” against the U.S. by China's Foreign Ministry.

China regards the FONOPs as sabre-rattling and “a challenge to [our] sovereignty,” according to Lt. Gen. He Lei, Beijing's lead representative at the Singapore conference.

He restated the government position on troops and weapons on islands in the South China Sea, describing the deployments as an assertion of sovereignty and said that allegations of militarization were “hyped up” by the U.S.

Philippine Defense Secretary Delfin Lorenzana stopped short of endorsing the FONOPs but told the Nikkei Asian Review that “it is our belief that those sea lanes should be left open and free.”

In contrast to Duterte's reluctance to confront China, his predecessor as president, Benigno Aquino, was frequently outspoken about China's increasing control of the sea. He pressed a case against Beijing to an arbitration tribunal in 2013 after a protracted naval stand-off the year before around Scarborough Shoal, a rock claimed by both countries and lying about 120 nautical miles off the Luzon coast.

In mid-2016 the tribunal dismissed China’s expansive “nine-dash line” claim to much of the South China Sea and its artificial island-building and expansion, all of which the tribunal said contravened the 1982 United Nations Convention on the Law of the Sea, or UNCLOS.

Duterte said he would not “flaunt” the tribunal outcome, in contrast with his campaign pledge to assert the country's sovereignty -- he even vowed to ride a jet ski to one of China's artificial islands and plant the Philippine flag there. Manila hopes for significant Chinese investment in roads, rail and ports, as part of Beijing's Belt and Road Initiative, a multicontinent plan outlining China-backed infrastructure upgrades.

Filipino activists rally outside the Chinese Consulate in Manila in February to protest Beijing's continued reclamation activities in the South China Sea. © Reuters

Defense Secretary Lorenzana emphasized in remarks to the media in Singapore that good relations with China remain a priority, regardless of bilateral disputes. “It is just natural for us to befriend our neighbor. We cannot avoid dealing with China, they are near, [and] many Filipinos, including me, have Chinese blood.”

For the Philippines, a U.S. treaty ally, there are growing doubts about whether the American navy would protect them in a conflict with China, something Duterte, a brusque critic of the U.S., has questioned publicly.

Mattis, like former President Barack Obama and his Secretary of State Hillary Clinton, sidestepped a question on that issue in Singapore, saying, “The reason why public figures do not want to give specific answers is that these are complex issues.”

American evasiveness is a reminder to the Philippines that the U.S. might not risk war with China over its old ally. “It is debatable whether Filipinos believe that the U.S. will have its back in a conflict with China,” Batongbacal of the University of the Philippines said. “Duterte's repeated statements against the reliability of the U.S. as an ally tends to undermine this further.”

Duterte's reticence has left Vietnam as the sole claimant willing to speak up. Discussing recent developments in the South China Sea, Vietnamese Defense Minister Gen. Ngo Xuan Lich told the Singapore conference, "Under no circumstances could we excuse militarization by deploying weapons and military hardware over disputed areas against regional commitments.”

Lich did not name-check China in his speech, but described “a serious breach to the sovereignty” of another country that “violates international laws, complicates the situation and negatively affects regional peace, stability and security.”

As well as hindering oil and gas projects in waters close to Vietnam, China's navy has for several years harassed Vietnamese fishing boats -- as it does around the Philippines -- and continues to occupy islands seized from Vietnam nearly five decades ago.

In 2014, anti-China riots kicked off across Vietnam after China placed an oil rig in South China Sea waters claimed by Hanoi. In early June there were demonstrations against proposals that protesters claimed will give Chinese businesses favored access in so-called Special Economic Zones in Vietnam.

The Lan Tay gas platform, operated by Rosneft Vietnam, sits in the South China Sea off the Vietnamese coast. China has been hindering Vietnam's oil exploration activities in the sea. © Reuters

Vietnam's response to potential isolation has been a cautious dalliance with the U.S. In late 2016, shortly before the election of Donald Trump as U.S. president, American warships docked in Vietnam's Cam Ranh Bay naval base, the first such visit since the former antagonists normalized ties in 1995. That landmark was followed in March this year by the arrival of a U.S. aircraft carrier to the central Vietnam city of Danang.

Hanoi recently called for greater Japanese involvement in the region's maritime disputes, perhaps signalling an interest in a wider effort to counter China. But unlike the Philippines, Vietnam, which like China is a single party communist-run state, is not a U.S. treaty ally. Historical and ideological differences mean that there are limits to how closely Vietnam will align with the U.S.

“I think there is a good momentum with defense cooperation with the U.S. But I don't think that it would immediately mean jumping into the ‘American camp,’ whatever it means,” said Huong Le Thu, senior analyst at the Australian Strategic Policy Institute.

From Bollywood to Hollywood

The U.S. has sought to widen the array of countries it hopes will join it in countering China’s rising influence. During his 12-day swing through Asia in late 2017, Trump peppered his speeches with references to the “Indo-Pacific,” dispensing with the long established “Asia-Pacific” label in favor of a more expansive term first used by Japan.

The "Indo-Pacific" was then mentioned throughout the U.S. National Security Strategy published soon after Trump’s Asia trip -- a document that alleged China aims to “challenge American power” and “is using economic inducements and penalties, influence operations, and implied military threats to persuade other states to heed its political and security agenda.”

Three days before his Singapore speech, Mattis announced in Hawaii that the U.S. Pacific Command would be renamed the Indo-Pacific Command, describing the expanded theater as stretching “from Bollywood to Hollywood."

Mattis later added some gravitas to the cinematic catchphrase, saying in Singapore that “standing shoulder to shoulder with India, ASEAN and our treaty allies and other partners, America seeks to build an Indo-Pacific where sovereignty and territorial integrity are safeguarded -- the promise of freedom fulfilled and prosperity prevails for all.”

The Trump administration clearly hopes for greater Indian involvement in its efforts to counter China's growing influence. Kori Schake, deputy director-general of the International Institute for Strategic Studies, said that while “Indo-Pacific isn't yet an established part of the lexicon,” the implications of the term are clear.

“India is an Asian power. The countries adopting the term are encouraging India into greater cooperation in maintaining the maritime commons in the Indian and Pacific oceans,” said Schake, a former U.S. State Department official.

Indian Prime Minister Narendra Modi addresses the Shangri-La Dialogue, an annual security conference, in Singapore on June 1. (Photo by Simon Roughneen)

Modi enthusiastically echoed American rhetoric about a “shared vision of an open, stable, secure and prosperous” Indo-Pacific, which he described as “a natural region” -- countering those who wonder if an area stretching from Bollywood to Hollywood might too vast and disparate to be cast into a geopolitical fact on the ground.

But Modi also heaped praise on China, despite its border dispute with India and increasingly close economic ties with Pakistan, India's neighbor and nuclear rival.

“Our cooperation is expanding. Trade is growing. And, we have displayed maturity and wisdom in managing issues and ensuring a peaceful border,” Modi said.

China's foreign ministry described Modi's speech as "positive," while one of its military delegation at the Singapore conference gloated that India and the U.S. "have different understandings, different interpretations, of this Indo-Pacific."

China's first domestically designed and built aircraft carrier © Kyodo

It is perhaps no surprise then that China's rivals in the South China Sea do not yet regard the nascent Indo-Pacific alliance-building as something to pin their hopes on when it comes to control of the sea.

“We are witnessing the great power shift toward Asia-Pacific with the 'Indo-Pacific strategy,' Belt and Road Initiative and a series of country grouping[s] in the region,” Lich said, cautioning that “the outcomes for the region and the world are somewhat yet to be unveiled.”

Lich's Philippine counterpart was even more circumspect, particularly regarding the Indo-Pacific concept. “I have to study it some more,” Lorenzana said. “This is a new construct in this area.”

Nikkei staff writers Mikhail Flores in Manila and Atsushi Tomiyama in Hanoi contributed to this article.