Territorial disputes in the East China Sea and South China Sea are fuelling a build-up in submarine fleets that can spark more frequent armed clashes in the already volatile waters, according to a US-based think-tank.
"The currency of naval power in the ESCS (East and South China seas) has become the submarine," Wikistrat, a consultancy that relies on "crowdsourced" analysts, said in its latest "simulation report".
With disputes in the region unlikely to be resolved soon via diplomacy, China, Japan and Vietnam will keep sending submarines to the East and South China seas in the next six years at least, it said. China claims almost the entire South China Sea, rejecting claims to parts of it from Vietnam, the Philippines, Taiwan, Malaysia and Brunei. It has a dispute with Japan over islands in the East China Sea.
Wikistrat said China, which has a current force of 64 diesel and nuclear-powered submarines, deployed three Jin-class ballistic missile submarines to the South China Sea earlier this year.
Vietnam, meanwhile, has taken possession of three Kilo-class attack submarines it purchased from Russia that it plans to send to the South China Sea next year.
Three more are scheduled to be delivered in two years.
China is expected to respond by sending its own Shang-class attack submarines that will, in turn, precipitate an escalation from Japan.
Japan could launch a new Soryu-class conventional submarine once a year, bringing the total number to 11 by 2020, according to Wikistrat. It already has 16 attack submarines in service.
The Philippines has been looking to place orders for three submarines since 2011. It has created a "submarine office", and it expects to have a small fleet operational in 10 years. It is, for the time being, focusing on building its anti-submarine capabilities.
The Philippines has earmarked 39 billion pesos (S$1.1 billion) to acquire two stealth missile-guided frigates, two anti-submarine attack helicopters and three gunboats that it intends to send to the South China Sea, the navy's weapons systems chief, Rear-Admiral Caesar Taccad, said recently.
The Philippines has kept its warships out of contested waters since its involvement in a two-month stand-off with China that saw it lose its foothold in Scarborough Shoal in 2012. Even non-claimant states like Australia and Indonesia are beefing up their underwater fleets.
Australia, which has a key interest in keeping the commercially vital South China Sea open, is buying up to 12 Soryu-class submarines from Japan. Indonesia has ordered three Type-214 submarines from South Korea to cover an area where China's so-called nine-dash line cuts across Indonesia's continental shelf.
Wikistrat analysts described the submarine build-up in the East and South China seas as "a potential parameter of instability". It ran four "master narratives" in its simulation, and the conclusion has been that China is making the East and South China seas "much more dangerous, for others and potentially for itself, by continuing to pursue militarily and diplomatically assertive means of change".
Vietnam will likely use its new submarines to run "denial operations" in the Paracel island chain off its coasts and around its military bases in the Spratlys.
Vietnam and China have been sparring for control over the Paracels. In May, China parked a US$1 billion (S$1.3 billion) mobile oil rig owned by state-run CNOOC oil company 240km off Vietnam's coast. China towed the rig back in July, but not before ships and fishing boats from both sides figured in dozens of ramming incidents, with one Vietnamese boat reportedly sunk.
Vietnam is hoping its submarines will deter China from moving as aggressively into its holdings in the Paracels and Spratlys, experts said.
China, however, is unlikely to hold back. Last Friday, the official China Daily reported that China is setting up an offshore observation network, including a satellite and radar station. The network, which covers "undersea observation operations", is set to be completed by 2020, the paper said.
Yet, apart from acting as a deterrent, submarines offer little return for small nations like the Philippines, considering their huge expense, experts said.
"Having a submarine is a prestige, but it is not pragmatic, considering our limited resources," said Mr Rommel Banlaoi, head of the Centre for Intelligence and National Security Studies in Manila.
This article was first published on December 22, 2014.
Get a copy of The Straits Times or go to straitstimes.com for more stories.