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The Utility of the US Navy’s Amphibious Assault Ships as Small-Deck Carriers

Ben Ho Wan Beng
RUSI Defence Systems, 25 August 2016
Aerospace, Air Power and Technology, Maritime Forces
With an overstretched nuclear supercarrier force, the US Navy’s Wasp- and America-class amphibious assault ships are increasingly being relied on to serve as light expeditionary aircraft carriers. This is a role in which these ships, perhaps unexpectedly, excel

On 1 August 2016, the US initiated an air campaign against the Libyan chapter of Daesh (also known as the Islamic State of Iraq and Syria, ISIS). The ongoing Operation Odyssey Lightning does not have a specific timeline; rather, it seeks to enable the UN-backed Libyan Government of National Accord to evict Daesh from the coastal city of Sirte. The campaign currently involves both fixed- and rotary-wing aircraft deployed on the amphibious assault ship, the USS Wasp, as well as remotely piloted air systems flying from land bases. As a result, Odyssey Lightning is a demonstration of the US Navy’s LHDs (landing helicopter docks) as de facto aircraft carriers for this kind of limited-intensity operation. These regularly feature in the contemporary operating environment, particularly in the Arc of Crisis – a region which, loosely defined, includes the coastal regions of the Indian Ocean.

The rising operational demands placed on the US Navy’s large-deck carrier force mean that the LHDs might be called on in the future to function as light aircraft carriers to cover any carrier ‘gap’ that might surface again. The US has ten nuclear-powered aircraft carriers (CVNs) and nine ‘amphibs’ (eight Wasp- and one America-class vessels) in service. There has been much discussion on whether ten supercarriers can grapple with the challenges of the global strategic environment – arguably more of these valuable vessels are needed.

With several CVNs being regularly overhauled or undergoing routine maintenance, only a few can be on station at any one time. For example, as of August 2016, only four out of ten American supercarriers were on active duty with the rest in their home ports. With demand often outstripping supply, it was no surprise that 2015 was the first time in eight years when there was a lack of carriers in the Gulf. Such scarcity was sidestepped earlier in 2016 only because the deployment of the Harry S. Truman strike group was extended. With further shortfalls looming, the LHD fleet could come in very handy in its light aircraft carrier role.

In fact the Wasp-class, with a displacement of approximately 40,000 tons and an air wing of about 30 Marine Corps fixed- and rotary-wing assets, is a small-deck carrier in all but name. This can also be said of the slightly larger America-class platform with a similarly sized aircraft complement. While an LHD’s air wing is relatively small, it is potent in its own right. For example, the Wasp-class regularly deploys with six AV-8B Harrier attack fighters, four AH-1 Cobra helicopter gunships and an assortment of transport assets such as MV-22 Osprey tilt-rotor aircraft and CH-53E Super Stallion helicopters. The tactical strike component of the vessel’s air wing is arguably more than capable of dealing with insurgents, militias and other irregular forces that characterise limited-intensity conflicts in the twenty-first century, and whose weaponry is usually limited to ‘technicals’ and shoulder-fired missiles.

It is undeniable that the Nimitz-class is a profound step up in terms of capabilities compared with the amphibs of the ‘gator navy’. The typical air wing of a Nimitz-class CVN consists of 44 F/A-18(E/F) (Super) Hornet attack fighters, four or five E-2C/D Hawkeye AWACS aircraft, several EA-18G Growler electronic warfare aircraft and over a dozen MH-60S Knighthawk utility helicopters. The vastly more potent airpower provided by a CVN compared with an LHD would be very handy for the entire spectrum of military operations. However, it might often be excess to requirements to deploy a large-deck carrier and its large air wing for ‘technical plinking’ and other light-strike operations – especially so given that the CVN force is already critically overstretched. Provided their range is adequate for the theatre and enemy air defences are not anticipated, helicopter gunships from an LHD would often be enough to attack enemy convoys, fighting positions and other insurgent targets of opportunity. In fact, gunships might actually prove more efficient than high-end strike fighters in such situations.

During the first 21 days of Operation Odyssey Lightning, a total of 74 air strikes were carried out against Daesh. This figure includes those conducted by land-based aircraft, and even if the USS Wasp’s aircraft had been involved in all 74 strikes, this works out to less than four per day. Such limited-intensity operations are likely to be common in such operations and, therefore, the sustained, high-tempo capabilities provided by supercarriers are not required. In addition, the Daesh assets hit during the air campaign so far have been predominantly troops and vehicles which perfectly fit the primary close-air support role of the gator navy’s tactical strike aviation. Therefore, while the CVN’s full-spectrum capabilities would be most welcome in any circumstances, the LHD is sufficient in these cases.

Furthermore, the LHD’s capability to carry a battalion of US Marines and the means to deploy it ashore – which CVNs lack – can be useful for operations below the threshold for high-end war-fighting which are currently endemic. Missions such as non-combatant evacuation, disaster relief, small-scale raids and combat search and rescue are all excellent examples. The medium- and heavy-lift rotary assets on LHDs, such as the CH-53E Super Stallion, are better suited for such operations than the MH-60 variants deployed on CVNs since their primary task is troop transport and support of ground operations. By contrast, troop transport is just one of the many roles of the MH-60S Knighthawk helicopters when on board a CVN. These duties also include anti-submarine warfare, search-and-rescue missions and cargo transport.

Critics might argue that LHDs are not as survivable as supercarriers against anti-access/area-denial (A2/AD) threats. However, it is worth considering if the A2/AD threat genuinely extends to the Arc of Crisis littoral where the US military is regularly deployed. In that region, only Iran has substantial A2/AD capabilities, and it is arguably not in its interests to fight a high-intensity conflict with the US in the foreseeable future.

Another aspect of the utility of the US amphibious assault ships was shown at the beginning of Odyssey Lightning. Harriers from the USS Wasp, together with MQ-9 Reapers flying from Jordan, were behind the air strikes on Daesh in Sirte during the campaign’s opening day on 1 August 2016. This was because the Italian government had yet to give permission to conduct strike missions from the nearest US air base to Libya – Naval Air Station Sigonella in Sicily. In fact, on the 2 August the Italian government was still only promising to ‘positively’ assess the use of Sigonella for Odyssey Lightning.

This case demonstrates to the aircraft carrier’s unique attribute: territorial independence and the concomitant ability to carry out air operations without being subject to possible host-nation restrictions that often constrain land-based air operations. Aircraft carriers, whether large- or small-deck, have their own logistical infrastructure and force-projection capabilities, and they are therefore an ideal tool for intervention in a crisis or conflict. This is especially true in cases where US interests are not the same as its allies; when such situations occurred in the past, Washington did not have access to air bases for combat operations - for example with Turkey during the 2003 Iraq War. In a similar fashion, it is possible that Italy might, for some reason, restrict, or even ban combat flights from the Sigonella air base. In such circumstances, the territorial independence offered by the USS Wasp would be even more important. Indeed, Rome had previously placed limitations on sorties emanating from its soil. For example, in February this year, it restricted US strikes against Daesh in Libya to only that of a ‘defensive’ nature to protect special forces.

The amphibious assault ship is likely to play an increasing role in protecting US interests in the future. An overworked carrier force means that there are simply not enough large-deck flat-tops to go around. The LHD fleet could alleviate this situation by standing in for its CVN counterparts in more permissive environments where the A2/AD challenge is limited, and where the tempo and intensity of operations required are lower. Some have suggested that most of America’s supercarriers should be sent to the Pacific where the shadow of China looms large, while most LHDs should operate in the southern European and Arc of Crisis littorals. Furthermore, with the declaration of initial operating capability with the US Marine Corps for the fifth-generation F-35B Lightning II, the US Navy’s LHDs are likely to become more effective as true light carriers in the years ahead.

Ben Ho Wan Beng
Senior Analyst with the Military Studies Programme at Singapore’s S. Rajaratnam School of International Studies.

The author can be reached at iswbho@ntu.edu.sg

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