The False Promise of Metrics

By Milan Vego

Counting the Guns

One metric coming increasingly into vogue is to count weapons carried by surface combatants. The system originated in England’s navy (the term Royal Navy was introduced in 1660) probably in 1604, when ships were organized into groups or “rates” according to the number of crew required to man them at sea. After 1660 the system changed so that ships were classified by their number of guns. In 1677 Samuel Pepys (1633–1703), Secretary to the Admiralty Board, revised ship classification according to both the number and weight of guns, which determined the size of the crew and, hence, the amount of pay and rations required. 1 Pepys’ system was revised half a dozen times, remaining in use until the mid-1800s. Other navies had similar systems; the French Navy categorized ships into five rates or rangs . But eventually the system was abandoned, as ships were organized by number of guns. 2

Recently some analysts adopted a revised-Pepys design as a so-called “combatant rating system” for the U.S. Navy’s surface ships. This would be based on the number of vertical launcher systems (VLS) carried on board surface combatants. These VLS were, it was claimed, similar in technological impact to the dreadnought of 1906. The Center for Strategic and Budgetary Assessments (CSBA) suggested dividing the entire battle force into seven rates: first-rate battleships (more than 100 VLS and/or 100 missiles); second-rate battleships (90–99 VLS and/or 90–99 missiles); third rate (60–89 VLS and/or 61–89 missiles); fourth-rate battleships or frigates (48–59 VLS and 48–60 missiles); fifth-rate frigates (20–47 VLS and/or 20–47 missiles); sixth-rate frigates for protection of shipping, armed with 8–19 VLS); and seventh-rate frigates for antisubmarine warfare, antisurface warfare, or general purpose, armed only with terminal defense such as rapid-fire guns or short-range surface-to-air-missiles.

In 2008, the CSBA maintained that the U.S. Navy’s superiority in terms of VLS cells was overwhelming. Of 101 surface combatants, some 70 carried 7,566 missiles. Among the next-largest 17 navies in the world, only 47 of 366 surface combatants in service were fitted with VLS, carrying only 1,552 cells. 3

There are several problems with the proposed rating system. Aside from being clearly limited to surface forces only, like other metrics it focuses exclusively on materiél. Any assessment of the intangible elements of combat potential is missing. The number of VLS carried by a ship does not show that these launchers can be used for launching Tomahawk long-range cruise missiles, Enhanced Sea Sparrow, or RIM-161 Standard Missile (SM)-3 Aegis ballistic missiles. It does not indicate whether particular surface ships have the capability to shoot down enemy cruise missiles or prevent attack by enemy submarines. Moreover, using VLS as a metric says absolutely nothing about a navy’s capabilities to perform antisubmarine warfare, defense and protection of maritime trade, use of mines, or countering a threat from enemy mines.

The CSBA also suggested counting aimpoints for assessing surface-combatant capabilities as whole or as individual platforms. One authority stated that in 1989, 13 U.S. aircraft carriers could hit 2,106 aimpoints; and by 2007, 11 carriers could deliver 7,623 aimpoints. However, experts acknowledge that the number of these points hit per day in real-world operations over a long range or in the face of a credible air defense would be much less than indicated. 4 Among other factors, the ability to hit a certain number of targets does not address the enemy’s ability to counter or avoid attack.

Aggregate Tonnage

Another evaluation method that started in the 17th century was measuring the fleet’s aggregate tonnage. Despite recent claims that this remains the best proxy for assessing overall combat capability, this is not the case. 5 A navy with an aggregate tonnage of less than 100,000, as the German and Royal Swedish navies have, cannot be said to be of lesser capability than is the U.S. Navy’s 100,000-ton Nimitz -class aircraft carrier. In 2008 the U.S. Navy, at 3.12 million tons, was the largest in the world. The next 17 accounted for 2.66 million tons. In other words, the U.S. Navy enjoyed a “17-navy standard,” displacing nearly as much as all the world’s in-service warships combined. 6 In 2008, the CSBA asserted that the Navy had a 2.63-to-1 advantage in fleet displacement and capabilities over the combined Russian-Chinese fleets. 7

Aside from the fact that an advantage in tonnage does not necessarily equate to a navy’s true capabilities, it is essentially useless to compare one navy to another in these terms because their missions across the range of conflict can vary so greatly. No other navy in the world today is called to perform as many diverse missions in almost all parts of the globe’s oceans as is the U.S. Navy. Hence, its strength must be distributed among several major theaters. High-intensity involvement in several theaters at the same time further reduces combat potential.

Shrinking Navy for a Big Job

As for tonnage, numbers of combatants indicate only roughly a navy’s capabilities. By the beginning of the Cold War, tonnage metrics had been abandoned in favor of ship numbers. In 1946, the U.S. Navy had 1,600 ships displacing 1,000 tons or more. Its main competitor, the Soviet Navy, grew moderately in terms of tonnage, but had in service a very large number of small submarines and coastal patrol craft.

Between 1961 and 1970, the U.S. Navy had in service between 932 and 743 ships, and in 1971–80 between 752 and 523. Its World War II ships had approached the end of their useful lives by the early 1970s and were replaced not on a one-for-one basis, but with smaller numbers of heavier, more capable, multi-mission ships. This trend was briefly reversed during the Reagan administration, when the goal was a 600-ship Navy. The battle Fleet reached its peak of 568 ships in fiscal year 1987. After the end of the Cold War in 1991, its strength declined steadily, to the point that by late August 2011, the U.S. Navy had in active service 284 ships, the smallest number since 1916. 8

The Navy traditionally emphasized larger, highly capable, and expensive platforms over smaller, low-capability, low-cost platforms. In mid-2010, its battle force consisted of 10 nuclear-powered aircraft carriers, 14 ballistic-missile submarines, 53 nuclear-attack submarines, 4 nuclear cruise-missile submarines, 22 guided-missile cruisers, 58 guided-missile destroyers, 30 guided-missile frigates, 3 littoral combat ships, 13 amphibious assault ships, 11 amphibious transport docks, 12 landing ship docks, and 14 mine countermeasures ships. 9

The Complexity of Assessments

Numbers alone do not show increased combat capabilities of individual platforms because of new technologies. A navy might be numerically very large but composed of small combatants, as was the case in the Soviet navy during the Cold War.

Aggregate numbers for a navy and ship types do not provide important information such as whether ships are optimally suited for operating in a given area. They do not reveal whether or not a navy is balanced. Currently the U.S. Navy has in service a relatively large number of surface combatants that could conduct a wide range of missions in a high-intensity conventional war. However, it lacks adequate capabilities for littorals, especially in narrow seas. Even a cursory look shows that the U.S. Navy’s surface force, both current and projected, is composed predominantly of large, highly capable, expensive platforms. Traditionally the U.S. Navy has emphasized the need for these ships, which are ideal for operations on the open ocean. Cruisers have become ever smaller, while destroyers have become progressively much larger. 10

Similarly, aggregate numbers of submarines do not indicate whether the force is optimally suited for operations in both deep and shallow waters. The U.S. force is composed entirely of nuclear-powered submarines, which are not the best platforms for shallow or confined waters.

Often both aggregate tonnage and numerical strength are used in estimating a navy’s combat potential. These two metrics alone do not show many other critical factors of combat potential, including the age, type, and size of ships; the lethality and effective range of weapons; whether the ships are single-, dual-, or multipurpose; the sophistication of sensors; the speed, range, and endurance; the quality of maintenance, and the availability of spare parts. Nor do they account for intangible aspects of naval potential, especially the human factor. Aggregate tonnage and numbers do not tell us whether naval leadership is predominantly focused on technology and tactics, or whether it has the knowledge and skills necessary for employing forces at the operational and strategic levels of war.

Additionally, these figures could be high on paper but less in practice, because of the country’s unfavorable strategic position at sea. For example, despite large aggregate strength, the Russian navy maintains four fleets in widely separated geographic areas. The Baltic and Black Sea fleets do not have direct access to the open ocean, and none can operate within mutually supporting distance of one other.

Navies’ missions can also differ considerably. For sea denial, large combatants and big numbers are not usually necessary. A weaker opponent at sea can effectively use non-naval capabilities such as land-based aircraft, ballistic missiles, coastal cruise-missile batteries, and mines in denying to a much stronger blue-water navy access to the littorals.

The People’s Liberation Army Navy (PLAN) recently completed trials for 1 aircraft carrier and already has in service 26 destroyers, 53 frigates, 55 medium and large amphibious ships, 49 diesel attack submarines, 5 nuclear-powered attack submarines, and 86 missile patrol craft. And the PLAN can be effectively supported by the PLA Air Force (PLAAF) and the 2nd Artillery Corps in denying the U.S. Navy control of the peripheral seas washing the mainland’s shore, as well as the South China Sea. The PLAN’s land-based aircraft combined with the PLAAF planes amount to about 1,680 fighters and 620 bombers/attack aircraft.

For strikes against naval and air bases, ports and logistical installations in the western Pacific, the 2nd Artillery Corps can use 75–100 1,100-mile-range medium-range ballistic missiles, 1,000–1,200 185 to 370-mile-range short-range ballistic missiles, and 930-mile-plus-range ground-land attack cruise missiles. 11 Reportedly the PLAN has in its inventories between 50,000 and 100,000 mines, produced in some 30 variants. 12 Hence, China’s anti-access capabilities are much greater than those posed by its navy alone. This illustrates that navy-to-navy comparisons of numbers of ships or aggregate tonnage can provide a highly inaccurate measurement of the true relative maritime capabilities. 13

Misleading Numbers

Overall, using various metrics is a highly questionable method in evaluating the U.S. Navy’s combat potential. Although they can provide some insight into capabilities, their numerous and serious deficiencies must be taken into consideration and addressed thoroughly. Even the decision about what to measure is highly subjective.

In short, metrics pertain only to the physical element of the U.S. Navy. They cannot be used to evaluate intangible aspects of combat potential and power that are hard to quantify. This is particularly the case with people.

Comparing navies in terms of aggregate tonnage and/or ship numbers or VLS cells is not useful. As the U.S. Navy performs numerous and diverse missions throughout the world’s oceans, it must contend with potential enemies’ naval and non-naval anti-access capabilities in littoral areas. Misleading and false data from metrics should not be used to justify decisions to drastically cut the size of the battle force.

If anything, the highly negative and rapidly changing global security environment, especially in the western Pacific, should be a wakeup call for the U.S. military and civilian leaders. Both Navy and Air Force capabilities should be not reduced but increased significantly, to conduct full-spectrum operations. The failure to face new challenges in the maritime domain is bound to greatly reduce our nation’s security, and eventually its prosperity as well.

1. N. A. M. Rodger, The Command of the Ocean. A Naval History of Britain 1649–1815 (New York and London: W. W. Norton, 2004), p. 220.

2. “Cruisers Are the Means of Exercising Control,” U.S. Naval Institute blog, January 2009, p. 2.

3. Statement of Robert O. Work, senior defense analyst, Center for Strategic and Budgetary Assessments, before the House Armed Services Committee, Projection Forces Subcommittee Hearing on DD(X), 19 July 2005, pp. 2–6.

4. Robert O. Work, Know When To Hold ’Em, Know When to Fold ’Em: A New Transformation Plan for the Navy’s Surface Battle Line (Washington, DC: Center for Strategic and Budgetary Assessments, 2007), p. 50.

5. Greg Grant, “CSBA’s $20 Billion a Year Shipbuilding,” DOD Buzz , 20 February 2009, p. 2.

6. Work, Projection Forces Subcommittee Hearing on DD(X), 19 July 2005, p. 1.

7. Robert O. Work, The U.S. Navy: Charting a Course for Tomorrow’s Fleet (Washington, DC: Center for Strategic and Budgetary Assessment, 2008), pp. 7–8.

8. Scott C. Truver, “Transformation: A Bridge Too Far?” Jane’s Navy International, 1 March 2005, p. 4. David T. Burbach, Marc DeVore, Harvey M. Sapolsky, and Stephen Van Evera, “Weighing the U.S. Navy,” Defense Analysis 17, no. 3 (2001): p. 259–60. Robert O. Work, Winning the Race: A Naval Fleet Platform Architecture for Enduring Maritime Supremacy (Washington, DC: Center for Strategic and Budgetary Assessments, 1 March 2005), p. 60.

9. “Navy,” Jane’s Sentinel Security Assessment: North America, 11 June 2010, pp. 33–35.

10. Ronald O’Rourke, Navy DD(X), CG(X), and LCS Ship Acquisition Programs: Oversight Issues and Options for Congress (Washington, DC: Congressional Research Service, Library of Congress, updated February 28, 2006), p. CRS-3.

11. Military and Security Developments Involving the People’s Republic of China 2011 (Washington, DC: Office of the Secretary of Defense, Annual Report to Congress, August 2011), p. 78.

12. Countering the Asymmetric Threat From Sea Mines (Washington, DC: Lexington Institute, March 2010), p. 4.

13. Testimony of Ronald O’Rourke, specialist in naval affairs, Congressional Research Service, before the U.S.-China Economic and Security Review Commission Hearing on the Implications of China’s Naval Modernization for the United States, 11 June 2009, p. 6.

Dr. Vego is a professor of operations at the Naval War College. Before coming to the United States in 1976, he served as commanding officer of torpedo boats and gunboats in the former Yugoslav Navy and as 2nd officer (Deck) in the former West German merchant marine. He is the author of Naval Strategy and Operations in Narrow Seas (London: Frank Cass Publishers, 1999 and 2nd ed., 2003) and many articles on littoral warfare.


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