MANILA - Two Japanese destroyers and one of the Philippines' newest warships began historic naval exercises in the flashpoint South China Sea on Tuesday, showcasing a deepening alliance aimed at countering a rising China.
The day-long war games, the first bilateral naval exercises between the former World War II enemies, took place less than 300 kilometres (186 miles) from a Philippine-claimed shoal now under Chinese control.
Philippine authorities insisted the exercises were merely focused on building military capabilities, but security analysts said they were clearly a signal to China over bitter maritime territorial disputes.
"First they demonstrate that China's Pacific neighbours are beginning to balance against China," professor Michael Tkacik, a foreign policy expert at the Texas-based Stephen F. Austin State University, told AFP.
"Japan, the Philippines, Vietnam, and assorted other states are threatened by China's behaviour, even as far away as India. Thus, the Philippines and Japan are jointly making an important statement about how seriously they view China's actions."
China has caused deep concern regionally in recent years as it has become more aggressive in staking its claims to the South China Sea and Japanese-claimed islands in the East China Sea.
China insists it has sovereign rights to nearly all of the South China Sea.
However the Philippines, Vietnam, Malaysia and Brunei have competing claims to parts of the sea, which is vital to the global shipping industry and is believed to contain huge deposits of fossil fuels.
In 2012, China took control of Scarborough Shoal, a rich fishing ground within the Philippines' exclusive economic zone and more than 650 kilometres from the nearest major Chinese landmass.
Chinese coastguard vessels have since guarded the shoal and denied Filipino fishermen access, triggering a series of protests from the Philippines that have been brushed aside in Beijing.
Although the Philippine navy declined to say exactly where Tuesday's exercises would take place, it said the vessels would sail into the South China Sea from the former US Subic Bay naval base.
That base is about 270 kilometres southeast of Scarborough Shoal.
A Philippine navy spokesman said the exercises were the first bilateral war games between the two nations.
He said one of the main drills would see an AW 109 helicopter from the BRP Ramon Alcaraz, a frigate acquired from the United States in 2012, flying to one of the Japanese destroyers when the three vessels meet at sea.
"It would be naive for anyone to think this is just an ordinary joint exercise in the light of some assertive actions by China in the South China Sea," Wilfrido Villacorta, an international relations lecturer at the Manila-based De La Salle University, told AFP.
He described this as a "natural reaction" by the Philippines after recent "provocations".
Villacorta cited in particular China's recent flurry of reclamation activities on reefs in the Philippine-claimed Spratlys archipelago, turning them into islands capable of hosting significant military outposts.
The Spratly islands are about 800 kilometres from Subic Bay.
Tkacik said Japan's naval presence in the South China Sea in support of the Philippines would likely anger China.
"We can fully expect loud protests from China about Japan aggravating the situation," he added.
"But in fact it is China that is ignoring international law and its actions are instigating this balancing behaviour between the Philippines and Japan."
China has repeatedly rejected allegations it is breaking international law in the South China Sea, insisting it has sovereign rights to the waters.
China and Japan are separately engaged in a bitter and longstanding row over ownership of a Japanese-controlled island chain in the East China Sea. They are known as Diaoyu in China and Senkaku in Japan.