We are, it seems, at the dawn of a new submarine age in Asia. Shifts in military strategies and acquisitions may be the work of decades, but recent weeks have seen several significant developments that highlight the potential for future tension in East Asia. Vietnam, Australia and the United States have all been involved in developments that are, in part, driven by China's military build-up. Russian news reports reveal a deal is close between Hanoi and its major cold war ally, Moscow, for Vietnam to buy six Kilo-class submarines - stealthy vessels that can be used for spying as well as hunting and attacking rival ships and submarines. If confirmed, it will mark Vietnam's first significant use of submarines - a move military analysts believe is a direct response to China's increased naval activity in the South China Sea, the site of a long-simmering dispute over the strategic Spratly and Paracel archipelagoes. Beijing's construction of a submarine base on Hainan Island has particularly alarmed Hanoi, analysts believe. Reports from the US, meanwhile, confirm that the Pentagon is continuing to transfer its own submarines from the Atlantic Ocean to the Asia-Pacific, with the USS Jacksonville the latest to move through the Panama Canal. By the end of this year, some 31 of the navy's 53 fast-attack submarines will be based across the Asia Pacific - a reverse of cold war era priorities. Pentagon intelligence chiefs have noted increased long-distance patrols by China's expanding 60-strong submarine fleet, but far fewer than the 100-odd long-distance patrols mounted annually by US submarines. China's patrols are closely monitored by Washington. The US has traditionally based its unparalleled projection of power on aircraft carrier battlegroups, rather than submarines alone. Military planners know submarines remain a devastating weapon with many uses, helping a nation provide a valuable stealth deterrent against a bigger potential foe. They can be used to tap undersea cables, release commandos or spies onto enemy shores while carrying missiles that can attack ships or, in the case of bigger submarines, cities. Nuclear-powered submarines can stay underwater for months if need be. The diesel-powered craft, such as the Kilo sought by Vietnam and already used by China, are far quieter, offering the advantage of surprise. That is thought to be vital in enclosed spaces, such as the South China Sea, where an aircraft carrier battlegroup and other large ships find it far more difficult to hide. 'Submarines give you options ... and, as the region starts to get a little hotter, that's what countries seem to want,' said one Asian military attach?. 'We are all watching each other. Every action in terms of a purchase or a plan sparks a reaction.' In Australia, meanwhile, military chiefs last week released a controversial white paper that calls for increased spending over the next two decades on a navy, led by a proposed fleet of 12 submarines. The move matches recent submarine expansions by Indonesia, Malaysia and Singapore. For anyone interested in regional security, it is a fascinating document, and reportedly marks a harder line than Australia's intelligence agencies would have liked. Despite recent years being dominated by the threat of terrorists and other so-called non-state actors, the paper warns of more traditional fears, noting the risk of a war within Asia over the next 20 years or so. It warns of likely tensions between regional powers 'where the interests of the US, China, Japan, India and Russia intersect'. 'The management of the relationship between Washington and Beijing will be of paramount importance for the strategic stability of the Asia-Pacific,' it adds. 'As other powers rise, and the primacy of the US is increasingly tested, power relations will inevitably change,' it states, warning of the risk of 'miscalculation'. 'There is a small but still concerning possibility of growing confrontation between these powers.' It notes the rising military, economic and diplomatic clout of China but, just as Australia has for decades, pins its colours firmly to America's mast, and therefore its other allies, such as Japan, too. 'The US will remain the most powerful and influential strategic actor over the period to 2030 - politically, economically and militarily,' the paper says. 'Its strategic primacy will assist in the maintenance of a stable global strategic environment. China, India, Russia, Japan and the EU will examine global influence of differing degrees and acquire varying levels of military strength to promote their interests.' Echoing US concerns, the paper also calls for more transparency from China about why it is modernising its military. Drafters were at pains to stress that China was not viewed as a threat, but rather a 'factor' in strategic considerations. Chinese envoys moved swiftly to reiterate Beijing's peaceful intentions. Within days of the paper's release, US defence chiefs were talking up the need for Washington to work even closer with its Pacific allies to respond to China's military growth. 'They [China] are developing capabilities that are very maritime focused, maritime and air focused and in many ways, very much focused on us,' Admiral Michael Mullen, chairman of the US Joint Chiefs of Staff, said in off-the-cuff remarks. For some, the recent standoffs in the South China and East China seas between mainland fishing vessels and US surveillance merely highlight the kind of tensions the report notes are building. Ian Storey, a fellow at Singapore's Institute of Southeast Asian Studies, said the report marked a clear 'shifting of the pendulum' back towards the idea of conflict within the region. 'They are really saying that war within the region can't be ruled out ... that, to my mind, is a very significant development.' Dr Storey said he believed the South China Sea was one potential area of conflict that needed to be better addressed diplomatically, noting Beijing's recent 'assertiveness' in backing its claims. Among other manoeuvres, Chinese diplomats last year approached executives from ExxonMobil, the world's largest oil company, and told them to withdraw from oil exploration deals with Hanoi off Vietnam's southern and central coast. They warned ExxonMobil's future mainland business could be at risk if they did not pull out. 'Over the past two years, the South China Sea dispute has moved from the back to the middle burner of Asian security issues,' Dr Storey said. 'If present trends continue, it may not be long before it is seen once again as a major potential regional flashpoint.' The South China Sea straddles internationally vital sea-lanes - including ships carrying the bulk of China's oil - and is home to potentially rich oil and gas reserves. Dr Storey, and several other regional scholars, has called for the Association of Southeast Asian Nations and China to strengthen their 2002 agreement not to act in any way to inflame tensions in the area. The declaration was widely hailed at the time but stops short of being a legally binding agreement. Regional defence chiefs are due to meet next month as part of Asean's annual Regional Forum on security. Few are expecting any action, however. The forum prefers to limit itself to confidence-building measures and humanitarian co-operation and there is no diplomatic push to broaden it. Carl Thayer, a veteran Vietnam watcher at the Australian Defence Force Academy, said he believed Asean members were far too preoccupied with other matters to tackle something as complex as the South China Sea at this point. 'It is certainly needed but, given the state of Asean, it is very hard to imagine,' he said. Asean's impotence is a further reminder of the lack of a meaningful security body across East Asia. Some have suggested turning the six-nation talks on North Korea - a grouping that includes China, the US and Russia - into a permanent body that regularly meets to diplomatically defuse any military tensions or uncertainty. Given problems with North Korea, that idea is unlikely to gain any further momentum soon. In the interim, regional militaries will continue to grow, placing their faith in submarines as they seek to keep closer tabs on their neighbours. 'In the region, we are all going to be debating China's intentions for years,' Professor Thayer said. 'The key thing here is capabilities. Once one country significantly changes what it can do, other countries improve their capabilities, too. If you don't, you risk not being able to protect your sovereignty. 'And that's where submarines become very, very useful.'