Silently hunting below the waves, the vessels are increasingly lethal and difficult to detect – submarines are one of the great tactical and strategic levellers. Patrolling groups of hunter-killers and at-sea deterrence force structures serve to enhance the specialisation and increasing capabilities of contemporary navies.
The highly successful campaigns of terror conducted by the German Navy's 'wolf packs' of submarines during the Second World War to the tactical and strategic brinkmanship between ever more deadly American and Soviet nuclear submarines during the Cold War have set the stage for the 21st century's race for strategic undersea dominance.
Modern combat submarines are typically broken down by role and either conventional or nuclear propulsion into three different classes, namely:
- Attack submarines (SSK/SSN): These vessels designed specifically to hunt and kill enemy submarines, surface combatants and merchant vessels. These submarines also serve a protective role, escorting major naval strike groups, logistics and troop convoys and merchant vessels. Recent advances in propulsion, power generation and weapons systems have also enabled these vessels to conduct long-range land strikes using torpedo or vertically-launched cruise missiles.
- Ballistic missile submarines (SSBN): Significantly larger than their smaller, more nimble hunter-killer focused cousins, ballistic missile submarines serve as the sea-borne leg of a traditional nuclear deterrence triangle, armed with submarine launched ballistic missiles – these submarines, often termed 'boomers', serve as the ultimate in strategic insurance for great powers like the US and China.
- Cruise missile submarines (SSG/SSGN): Often modified ballistic missile submarines, cruise missile submarines leverage the unlimited range of nuclear powered vessels combined with advances in weapons technology to pack vast numbers of land attack and anti-ship cruise missiles into specially modified vertical launch systems to provide immense levels of conventional strike capabilities.
As both great and regional powers scramble to design and build, or buy and introduce, the latest and most capable submarine platforms to ensure their continued dominance, maritime security and ability to deter potential adversaries, Australia's changing strategic environment has raised questions around the survivability, cost and capability of the Royal Australia Navy's ageing Collins Class submarines and the relevance of Australia's future Attack Class submarines.
Developing complementary force structures – focused on dedicated hunter-killer, at-sea deterrence patrol groups – serves to enhance the Navy's existing Collins Class vessels, while laying the foundation for enhanced capabilities following the introduction of the Attack Class, expected for the mid-to-late 2020s.
Submarine squadrons – America's silent assassins
The US Navy operates a number of different submarines in the Indo-Pacific region, including fast-attack submarines, ballistic missile submarines and cruise missile submarines, which are responsible for providing surface fleet anti-submarine warfare cover, strategic deterrence and long-range strike capabilities – broken up into eight different submarine squadrons.
However, a large portion of the US Navy's submarine fleet is made up of Cold War-era vessels, designed to patrol, hunt and stalk their Soviet counterparts in the north Atlantic, an operating environment vastly different to that of the Indo-Pacific. In response, the US has embarked on a period of rapid modernisation for the submarine fleet, with new Virginia Class attack submarines delivered almost annually and design progress on the next-generation Columbia Class ballistic missile submarines ever closer to beginning construction.
America's forward deployed submarine squadrons – typically those based at Pearl Harbour, San Diego and Guam – all operate between five and 11 fast attack submarines designed to escort carrier and expeditionary strike groups or conduct individual or combined long-range patrols throughout the Pacific in support of deterrence patrols, while providing conventional long-range strike and maritime interdiction options for combatant and strategic commanders.
Setting the foundation with Australia's Collins Class – Enhancing range and basing
Australia's comparatively moderately sized fleet of Collins Class submarines has provided Australia with a relatively inconsistent at-sea deterrence force since the introduction of the first vessel, HMAS Collins, in the mid-1990s. Despite early teething issues, the fleet of six submarines are an important component of Australia's enduring strategic force multiplying arsenal – however, they have historically been limited by crewing, range and forward deployment basing.
Recognising these challenges, namely the limited range as a result of forward deployment and basing arrangements, can be readily overcome by enhancing Navy infrastructure at key facilities, such as Darwin, the Cocos Islands and Cairns, in close proximity to submarine patrol grounds and establishing forward deployment arrangements with regional allies including the Philippines, Vietnam, Singapore and critically Japan.
Further enhancing the deterrence patrol capabilities is the potential for reorganisation of the submarine force to focus on keeping a minimum of two vessels at sea at any one time with a surge capacity for an additional two submarines to be put to sea on short notice to support hunter-killer, deterrence or task group escort duties.
Each of these changes serves to address some of the issues facing the tactical and strategic effectiveness of Australia's submarine fleet, establishing a force structure and operating doctrine that can be perfected prior to the introduction of the Attack Class submarines – further empowering the "regionally superior" capability to be delivered to the Navy.
Maintaining the regional order and enhancing Australia's national interests
However, the question now becomes, given the geographic area of responsibility Australia will become increasingly responsible for and dependent on, is the RAN and the recapitalisation and modernisation programs currently underway enough for Australia to maintain its qualitative and quantitative lead over regional peers?
It is clear that Australia's region is going to be increasingly congested as both great and emerging powers continue to invest heavily in their own submarine capabilities. The growing proliferation of steadily more capable platforms across the nation's northern approaches presents significant challenges for the nation's existing Collins Class submarines in the short-to-medium term and the future submarine force of the future.
Australia is defined by its relationship and access to the ocean, with strategic sea-lines-of-communication supporting over 90 per cent of global trade, a result of the cost effective and reliable nature of sea transport. Indo-Pacific Asia is at the epicentre of the global maritime trade, with about US$5 trillion worth of trade flowing through the South China Sea and the strategic waterways and choke points of south-east Asia annually.
The Indian Ocean and its critical global sea-lines-of-communication are responsible for more than 80 per cent of the world's seaborne trade in critical energy supplies, namely oil and natural gas, which serve as the lifeblood of any advanced economy.