Defending the carriers

With Britain's Queen Elizabeth class aircraft carriers not due to enter service for nearly a decade and talk of strong new threats to carriers emerging, Dr Lee Willett, Head of RUSI's Maritime Studies programme, examines their viability

The United Kingdom's two Queen Elizabeth class aircraft carriers survived the 2010 Strategic Defence and Security Review (SDSR) – but only just. Despite the demonstrable strategic value of two highly flexible flat-topped ships in meeting a range of UK tasks from the high end to the low end of the spectrum, the carriers' fate hung in the balance right until the very end of the review. Even today, their fate may still not be secure. Despite carriers' demonstrated utility in Kosovo, Sierra Leone, Iraq, Afghanistan, the Asian tsunami, Hurricane Katrina, the Lebanon, Haiti and the ash cloud, questions continue to be asked about their strategic value. 

These questions generally can be grouped under two broad assumptions. The first is that they are expensive, inflexible Cold War relics. Yet £5bn to build two ships which can show the strategic flexibility to adapt to a range of circumstances and conflicts over up to 50 years of life demonstrates extremely good value for money. For example, the US Navy carrier USS Enterprise (CVN-65) is 49 years old, has more deployments due, and has seen active service during the Cuban Missile Crisis, Vietnam and Afghanistan – each a different crisis requiring a different response.

The second assumption is that carriers are militarily vulnerable. This article will address this second question.

It may be quite hard to sink a 100,000 – or 65,000 – ton ship. It is for this reason that the Soviet Navy carried nuclear-capable anti-ship cruise missiles during the Cold War, to help break free from the grip of the carrier-based vice that the US Maritime Strategy would place around the Soviet Navy's access to open water. However, in reality the requirement should not so much be to sink a carrier but just to stop its aircraft from flying. With this in mind, even a kinetic energy projectile penetrating the flight deck might prove to be enough.

The discussion of carrier vulnerabilities has raised the profile of several major anti-ship cruise and ballistic missile programmes. These include the joint Indian-Russian Brahmos super- and hyper-sonic cruise missile, the Russian SS-N-27 Klub cruise missile, the Chinese C-802 cruise missile and – perhaps most notably – the Chinese Dong Feng-21D anti-ship ballistic missile. This is not a hypothetical threat either: Hezbollah used a C-802 to sink an Israeli warship in the Lebanon crisis in 2006. Reflecting Cold War era Soviet thinking, the Chinese People's Liberation Army (Navy) strategic logic seems to be to develop such weapons as an anti-carrier capability, to give them an option for releasing the operational pressure likely to be created by the presence of several US carriers in the event of any high intensity conflict. In both strategic terms, such developments are not new. What is new, though, is the technology – both in terms of the missiles themselves and the systems intended to defend against them.

However, there are still two basic – and fundamentally erroneous – assumptions in the argument that short-range missiles provide a direct, indefensible threat to aircraft carriers. The first is that an aircraft carrier is a static, lone platform which anchors just offshore. In reality, an aircraft carrier has the ability to sit well over the horizon in the vastness of the ocean. Simply, finding a ship in large areas of water is tricky. Indeed, while a lot of the counter-carrier arguments in the SDSR appeared to emanate from proponents of funding more capability on the ground in Afghanistan, retired Army officer Patrick Hennessey noted in his acclaimed book The Junior Officers' Reading Club, while visiting a deployed Royal Navy carrier, that he "marvelled at how tiny and insignificant the little grey box ... was against the expanse of the ocean". Using tanking support, which it can carry itself if needed (as shown by the way in which the US Navy uses modified versions of its own F/A-18 Hornets to provide an indigenous tanking capability) a carrier can project power at ranges sufficient to allow it to stand well offshore. It also can move over 500 miles per day. So a carrier would not be a stationary, close-in target. There is also the question of whether a potential opponent has sufficient intelligence, surveillance, target acquisition and reconnaissance (ISTAR) capability to be able to find, fix and strike a carrier with the requisite degree of surety and with enough redundancy to deal with jamming capabilities. In terms of conventional anti-ship missiles, the reduced firepower compared to a nuclear weapon means that the missiles would also require a much greater degree of accuracy to ensure they find their target.

Second is the fact that this argument ignores the offensive and defensive capability of the carrier's battle group – its own dedicated self-defence unit. The carrier sits offshore behind this potent screen of offensive and defensive firepower. In the case of the UK's carriers, in combat circumstances the ship would likely be accompanied some of the most advanced warships in the world: an Astute-class submarine, able to deal with both surface and underwater targets; and one or maybe two Type 45 Daring-class air defence destroyers, with an anti-air warfare defensive suite with the potential to be developed to deliver an anti-ballistic missile capability. The short range of most of the anti-ship weapons means that their launch platforms would need to be much closer to the carrier itself, thus increasing significantly their own exposure to the defensive capabilities of the battle group.

The reality is that a potential adversary will have to first find the carrier and then negotiate heavy layers of defence which will need to be peeled away. Thus, making a carrier vulnerable may not be as simple as sometimes is assumed.

Yet, despite these challenges, major powers are continuing to develop an anti-carrier capability. The Chinese DF-21D is the most prominent example. While its capability and in-service date remain open to question, its 900-mile range from its land bases mean that there is no need to deploy a ship within range, or inside the range, of the task group. 

However, elements of the task group – such as land attack cruise missiles (such as the Tomahawk missile carried by the Astute boats), Joint Strike Fighters launched from the carriers themselves or the revived US conventional long-range bomber programme - can still hold land-based launch sites at risk. In terms of ship-based systems, the issue of having to deal with the defensive firepower of the task group itself is perhaps demonstrated by developments in the Russian SS-N-27 Klub-M anti-ship cruise missile programme. The missile can be fired from shipping containers. While generating this extra versatility – in terms of being able to fit warships with the weapon more quickly and cheaply – is probably the principal reason for this development, an added bonus would be the ability to position the weapon more discreetly, perhaps on land at a choke point or perhaps more notably on a commercial ship which might have a greater chance of getting further inside a carrier's defensive shield.

Whether the capabilities of these new weapons will be proved in due course to be credible, there has been some debate as to whether their emergence would be a game changer in terms of rendering carriers obsolete. It seems more likely that such developments will impact more on the modus operandi of a strategic asset such as a carrier, but this is where such weapons may have greater benefit as a tactical deterrent, giving a potential sea denial capability – for example reducing the desire of the US Navy to commit carriers into the Taiwan Strait in the event of a clash over Taiwan.

Perhaps the most significant questions in terms of carrier vulnerability is not anti-ship missiles, but submarines. Notwithstanding, in China's case, its building of large numbers of nuclear-powered and conventional-powered attack submarines (SSNs and SSKs) and notwithstanding the Chinese Song-class SSK found shadowing the USS Kitty Hawk carrier and its battlegroup in 2006, the challenge here for Western navies relates more to its own reducing focus on Anti-Submarine Warfare (ASW) as a discipline. Seen superficially as once again a Cold War requirement, following the collapse of the Soviet Navy at the end of the Cold War and to ward off arguments that Western SSNs were Cold War relics, major Western navies began adding to the tasking list of SSNs, including roles such as land attack. A consequence of this was a decline in submarine-based ASW skills sets. With other nations and navies around the world seeing submarines – especially those purchased off the shelf and particularly from the West – as a way of jumping the queue in terms of naval power, the threat to aircraft carriers may come more from below the surface than above it. Submarines are of course a principal platform for anti-ship cruise missiles, raising the issue of the threat from missiles such as the Brahmos and the Klub from a platform far better equipped to sneak into range.

Whatever the conclusions of this debate, the fact that key nations are placing a high priority on a range of anti-carrier capabilities certainly does one thing: it highlights the enduring strategic utility and importance of the carriers themselves.