The decision to acquire 12 new submarines was one of the main outcomes from the 2009 White Paper. Other than to build the new vessels in South Australia, few aspects of the Future Submarine program have been decided. Three main options remain under consideration: a completely new, bespoke design, an ‘evolved’ Collins class, and a MOTS (modified off the shelf) European boat that is cheaper, but also less capable in terms of range, endurance, sensors and combat system than the other alternatives.

What these new boats are supposed to do has received far less attention in the debate. Andrew Davies, Ben Schreer and Peter Briggs are to be commended for drawing attention to the link between the submarine options under consideration, and the role, if any, that Australia intends to play in the emerging US posture in Asia. Andrew and Ben imply that Australia’s strategic focus on northeast versus Southeast Asia will have direct implications for the choice of design. That seems intuitive if the distance between Australian ports and those two areas is the main criterion. The question, however, is whether this intuition is correct. A definitive answer to this question is beyond what can be achieved in a blog post (and beyond my expertise), but it's nonetheless useful to examine this assumption in greater detail.

It seems reasonable to assume that anti-surface and ASW operations in Northeast Asia, i.e. around Taiwan and in the Yellow Sea, would be the most demanding tasks, in terms of range and endurance, for Australian submarines operating from Australian bases. The key question is whether and why operations that focus on Southeast Asia instead would be any less demanding. Benjamin and Andrew both assume that Australian submarines would operate in ‘maritime chokepoints’ in the region. But before we determine the best operating area, we must first ask what Australian submarines are to achieve?

Andrew raises the distant blockade of Chinese shipping as one possible task that submarines may perform in that region. However, traffic entering the Malacca or Lombok Straights could be heading for a number of friendly countries, and submarines are a less than ideal tool to discriminate hostile from neutral shipping, as Germany found in the WWI. In terms of discrimination and cost-effectiveness, it's hard to beat boarding teams operating from surface vessels, or even from bases in regional countries. Submarines are singularly good at sinking other ships, and excellent ASW platforms, but neither makes them very suitable to enforce a distant blockade in Southeast Asian chokepoints. If they are to contribute to the destruction of Chinese shipping, they would have to do so in maritime exclusion zones without neutral shipping—in other words, directly off the Chinese mainland, rather than in Southeast Asia.

A second possible operational objective that Australia might want to achieve in or around Southeast Asian maritime chokepoints is the protection of friendly shipping. Even in times of conflict, Australian partners—including Singapore, the Philippines and Vietnam—will need to maintain sea lines of communication through the South China Sea. If Australia has to continue importing refined fuels from Singapore, or sustain air or land forces in Southeast Asia, it too would need to protect shipping in regional chokepoints. RAN frigates and AWD might protect ships in company from Chinese attack, but the destructiveness and range of modern weapons makes this difficult, and it's better to ‘shoot the shooter, not the arrow.’ In a layered defence system, it's reasonable to assume that submarines would operate as the first line of defence. If friendly shipping is in the chokepoints, Australian submarines would again have to operate further to the North, well into the South China Sea.

Finally, Australia will also want be to prevent Chinese naval vessels, and Chinese nuclear submarines in particular, from threatening Allied shipping in the Indian Ocean. The question is whether maritime chokepoints in Southeast Asian are the best place to conduct ASW—local environmental conditions make it a very challenging place to detect submarines. During the Cold War, with far better hydrographic conditions in the UK-Iceland-Greenland gaps, US submarines still sought to intercept their Soviet counterparts right outside the Soviet harbours. And Chinese nuclear submarines could approach Australia and the Indian Ocean through the Pacific and Southern Ocean. Again, Australian submarines might well have to operate directly off the Chinese mainland to achieve operational objectives in Southeast Asia and the approaches to Australia.

Andrew and Benjamin are right that Australia needs to confront difficult questions of politics and strategy, if it's to determine the most cost-effective option for its Future Submarine. But the operational and tactical considerations of how to achieve Australia’s operational objectives, once decided, are equally important. Even if Australia doesn't want to directly participate in the maritime battle in Northeast Asia, its submarines might well have to be able to operate off the Chinese mainland to achieve its objectives in Southeast Asia. This has implications for the required range, endurance, combat system, sensors, weapons load, quieting etc. Range is but one criterion driving submarine size, and could be mitigated through forward basing. But the undersea endurance required to operate in the Northern part of the South China Sea, or the power and space needed to operate towed arrays and other sensors optimized for operations in warm tropical waters, have little to do with range.

Governments shouldn't accept unsubstantiated claims that only a solution with all bells and whistles will do. But they should be equally sceptical of the assumption that limiting operational objectives to Southeast Asia will automatically mean that lesser capable designs become more cost-effective. In one point, however, Andrew, Ben and I are in complete agreement: in determining the most cost-effective option, the government must decide what exactly Australia wants the new submarine to do, where and against whom. That requires it to decide how it intends to use the ADF to achieve its strategic objectives in the ‘Asian Century’ and, in turn, that requires it to decide what strategic role it sees Australia playing in the emerging power struggle in Asia. This involves analysis and judgment of questions of broadest, national grand-strategy, and also highly specialised tactical and technological detail: exactly what Defence White Papers are for.

Stephan Fruehling is senior lecturer at the Strategic and Defence Studies Centre, ANU. Image courtesy of Flickr user Chairman of the Joint Chiefs of Staff.