Philippine navy will soon return to a South China Sea island it lost to Vietnam 40 years ago to drink beer and play volleyball with Vietnamese sailors, symbolising how once-suspicious neighbours are cooperating in the face of China's assertiveness in disputed waters.
Diplomats and experts describe the nascent partnership as part of a web of evolving relationships across Asia that are being driven by fear of China as well as doubts among some, especially in Japan, over the U.S. commitment to the region.
When U.S. President Barack Obama visits Asia this month he will see signs that once-disparate nations are strategising for the future, even though he will likely seek to shore-up faith in America's "pivot" back to the region.
Among the new network of ties: growing cooperation between Japan and India; Vietnam courting India and Russia; and Manila and Hanoi, the two capitals most feeling China's wrath over claims to the potentially energy-rich South China Sea, working more closely together. The Philippines and Vietnam are also talking to Malaysia about China.
"We are seeing a definite trend here, one that is likely to accelerate," said Rory Medcalf, a regional security specialist at Australia's independent Lowy Institute for International Policy in Sydney.
"It is quite a creative dance as countries hedge and try to cover themselves for multiple possible futures."
While it was unlikely the new-found relationships would become military alliances, there was an intensity to their strategic discussions, including the sharing of assessments about China's rise and influence, Medcalf said.
Regional diplomats confirmed increasing levels of trust at a working level, as countries find that China's projection of naval power into Asia's waters is driving them together.
That trust will be on display in early June on Southwest Cay, a Vietnamese-held island in the Spratly archipelago of the South China Sea.
In early 1975, forces from then South Vietnam took Southwest Cay by stealth when its occupiers, a Philippine naval detachment, sailed a couple of miles to Northeast Cay, which was under Manila's control, for a party.
The South Vietnamese were soon displaced by the communist forces of a victorious Hanoi and the new Vietnam and the Philippines found themselves on opposite sides of the Cold War for many years.
A 40-strong Philippine naval delegation will return to Southwest Cay to party - this time to mark budding naval cooperation between Hanoi and Manila even though both still claim the island, Philippine and Vietnamese military officials told Reuters.
They said a day of beach volleyball, drinks and music was being planned in a celebration unprecedented in the recent history of the Spratly islands.
The precise date of the party on Southwest Cay, which is almost equidistant from Vietnam and the Philippines, has yet to be finalised, the military officials said. The Chinese navy had not been invited, they added.
"We actually had this scheduled last year but Typhoon Haiyan intervened ... We are lining up more activities in the future," said a senior Philippine naval official who declined to be identified because he was not authorised to speak publicly.
While the Philippines, Malaysia and Brunei each claim some of the Spratly islands, China, Taiwan and Vietnam lay claim to the entire chain.
China also claims 90 percent of the 3.5 million sq km (1.35 million sq mile) South China Sea, its reach displayed on its official maps with a so-called nine-dash line that extends deep into the maritime heart of Southeast Asia.
China has a separate dispute with Japan in the East China Sea over uninhabited islets that are administered by Tokyo.
Doubts about Washington's future willingness and ability to defend Japan simmer beneath the surface in Tokyo, although Japanese and U.S. officials routinely say the U.S.-Japan alliance is the cornerstone of regional security.
China, for its part, accuses the various claimants of stirring up trouble. Defense Minister Chang Wanquan, at a news conference with U.S. Defense Secretary Chuck Hagel in Beijing on Tuesday, called on Washington to restrain Japan and chided the Philippines.
Diplomats and experts believe Beijing will be watching the Manila-Hanoi rapprochement closely, having earlier protested the prospect of Philippine-Vietnamese exercises around Southwest and Northeast Cay when they were first mooted in 2012.
The two navies recently agreed to expand cooperation in disputed areas and a Vietnamese guided missile cruiser will soon visit Manila, Philippine naval officials said.
The head of the Philippine military, General Emmanuel Bautista, plans to visit Hanoi next month, Philippine officials said.
Philippine Foreign Secretary Albert del Rosario told Reuters on Monday that both Manila and Hanoi were also reaching out to Malaysia to swap notes on how best to deal with China.
He said he hoped the three could eventually settle their own South China Sea disputes amongst themselves, something that would strengthen their hand in responding to China.
"If we get there, we get there," he said. "That's a good opportunity for us."
The Vietnamese Foreign Ministry said it did not yet have information on the planned Spratlys party.
Vietnamese envoys and sources close to the Malaysian government said both Kuala Lumpur and Hanoi, meanwhile, were watching Manila's move to challenge Beijing's claims to the South China Sea at an international arbitration tribunal.
Manila filed the case late last month with the Permanent Court of Arbitration at The Hague. China has refused to participate.
Patrick Cronin, director of the Asia and Pacific Security Program at the Center for a New American Security in Washington, said cooperation among the Philippines, Malaysia and Vietnam was likely to grow, although it would remain modest.
"Together, they may be able to convince China that it needs to stop using risky and unilateral coercive means to change the facts on the ground and the sea," he said.
Medcalf, of the Lowy Institute, said that for all the new alignments, there were clear limits.
Countries wanted improved relations with China even as they hedged against trouble ahead.
To that end, no-one was talking about new actual alliances beyond existing U.S. treaties with Japan, South Korea, the Philippines and Thailand.
"China is not involved in these conversations, that is clear ... But would the other partner take strategic risks over China on behalf of one of its new friends? I don't think we are there yet," Medcalf said.
China was concerned, but not overly so, said Zhang Baohui, a mainland international relations expert based at Hong Kong's Lingnan University.
"China knows it is the most important economy in the region and that means it is important for other countries to improve relations with it," Zhang said.
"And aside from perhaps Japan, no other country sees China as an outright threat to its national security, even though they might be worried about its military rise." (Additional reporting by Martin Petty in Hanoi. Editing by Dean Yates)