Research Story of the Week

North Korean Cruise Missile Tests--and Iraqi Cruise Missile Attacks--Raise Troubling Questions for Missile Defenses

Photo [Source: www.globalsecurity.org]
HY-2 cruise missle.
[Source: www.globalsecurity.org]

By Dennis M. Gormley

Although U.S. Secretary of State Colin Powell characterized North Korea's February 24 launch of two anti-ship cruise missiles into the Sea of Japan as "fairly innocuous," there are good reasons to heed North Korean cruise missile activities. The chief one became evident on March 20, nearly 5,000 miles west of the Sea of Japan, in Iraq. There, amidst several Iraqi ballistic missile attacks against U.S. invasion forces--most of which were intercepted by Patriot anti-missile batteries--Iraq launched a cruise missile of roughly the same vintage as North Korea's. Flying low to avoid detection by Patriot radars, the cruise missile landed dangerously close to a Marine encampment in Kuwait.[1] This successful penetration of American defenses was not a freak occurrence. The Iraqis succeeded once again in the early morning hours of March 28, when another Chinese-provided cruise missile hit--without warning--close enough to a Kuwaiti shopping mall to shatter windows.[2] Three more cruise missiles were fired into Kuwait on the evening of April 2.[3] Despite the fact that these cruise missile attacks did not cause any casualties, they demonstrate forcefully that ballistic missiles are not the only means of long-range delivery by which countries might threaten the United States and its regional partners. It also points to the unique challenges of detecting and shooting down low-flying cruise missiles without doing the same to our own or allied aircraft.

The North Korean Missile Tests

North Korea routinely conducts missiles tests between March and November, yet it is difficult to dismiss the notion that the recent North Korean tests were devoid of any emergent political and military content. The February 24 test occurred on the evening before the inauguration of South Korean president Roh Moo-hyun; the March 10 test happened a little over a week after North Korean jets threatened a U.S. RC-135 reconnaissance aircraft; and the April 1 test came in the immediate aftermath of Japan's launching of its first spy satellites. All occurred in the larger context of Washington's nuclear deadlock with Pyongyang.[4] Given the presence of U.S. Navy ships in the Sea of Japan, North Korea conceivably may also have sought to remind the United States that the North Korean People's Navy possesses threatening missiles.[5]

What the North Korean People's Navy test fired into the Sea of Japan on February 24, March 10, and April 1 appears to have been the HY-2 Seersucker, a large, bulky anti-ship cruise missile lineally descended from the Soviet Union's P-15 Styx anti-ship cruise missile, developed after World War II.[6] The HY-2 is a Chinese derivative of the Styx; the program began in the mid-1960s and was initially declared operational in 1970. China has exported the HY-2 widely, including to North Korea and Iraq. It is uncertain, however, whether North Korea has received more advanced versions of the HY-2. Depending on the variant, more advanced models include an infrared seeker, radio altimeter, TV guidance, and improved active radar guidance.[7] The HY-2 has a liquid- propellant engine that attains a velocity of Mach .9 (nearly the speed of sound), while propelling the missile to a range of 95 kilometers. Its launch weight is nearly 3,000 kilograms (including a warhead weighing just over 500 kilograms), while its airframe is 7.36 meters long, .76 meters wide, with a wingspan of 2.4 meters--all of which merit the description, large and bulky. By contrast, more modern Chinese anti-ship cruise missiles, such as the C-801 and C-802--which possess characteristics not unlike the ubiquitous French Exocet cruise missile--have launch weights that are roughly a quarter of the HY-2's.

North Korea has not only developed the capacity to produce the HY-2 missile on its own, but has also modified the original design to achieve a longer range. In June 1994, North Korea surprised Western intelligence officials when it first tested an indigenously modified Seersucker to a range of 160 kilometers.[8] Over three years later, Western intelligence dubbed the missile the AG-1, when the system was tested again to a range of roughly 200 kilometers. Potential buyers from Iran and other countries reportedly witnessed both the 1994 and 1997 tests of the modified HY-2.[9] Whether the recent spate of tests involved the modified AG-1 or unmodified HY-2 missiles remains unclear.[10]

Making a Virtue of Necessity

The consensus is that the North Korean cruise missile developments were benign, in line with Secretary of State Colin Powell's "fairly innocuous" characterization. Similarly, Japanese Defense Agency Spokesman Manabu Shimamoto told the Associated Press that the April 1 launch was not a direct threat because it was "impossible" for it to reach Japan.[11] But such a sanguine assessment of North Korea's cruise missile tests is more a product of political calculation than one of military analysis. It is true that Japan and the United States worry much more about North Korea's Nodong and Taepodong-2 ballistic missiles, which are capable of reaching each nation's respective territory. Nonetheless, Iraq's surprising use of HY-2 anti-ship cruise missiles to attack land targets in Kuwait suggests that the threat from anti-ship cruise missiles should not be dismissed as readily as it has been. Countries wishing to threaten their neighbors, or indeed adversaries located virtually anywhere around the globe, could make a virtue out of necessity by transforming seemingly innocuous anti-ship cruise missiles into vastly more effective means of delivery than Iraq's cruise missile attacks have proven thus far. Just how conceivable such a scenario might be and what consequences it might augur are worthy of analysis.

Turning cruise missiles designed originally to attack ships at sea into ones that attack targets on land is nothing new. The U.S. Navy has transformed the ubiquitous Harpoon (exported to 24 nations) anti-ship cruise missile (AGM-84) into the Stand-off Land-Attack Missile (SLAM/AGM-84E). Russia's export family of anti-ship cruise missiles, called Klub, has a dual-mode feature on at least one version--the jointly produced Russian/Indian Brahmos cruise missile--that permits both an anti-ship and land-attack capability.[12] Yet these conversions are not broadly representative of what North Korea might be able to do with a portion of its existing inventory of HY-2 missiles. Modern anti-ship cruise missiles like Harpoon, the French Exocet, and even the Chinese C-802 are considerably smaller in overall size and space than most modern land-attack cruise missiles. The Harpoon, Exocet, and C-802 are already densely packed with integrated electronics, which leaves little room for the kinds of changes required to convert an anti-ship into a land-attack missile while appreciably extending its range. Although the Harpoon's conversion to the SLAM, for example, permitted the SLAM to be used very accurately over land, the Harpoon's 100-kilometer range was not altered.

Available press reports show no evidence that the Iraqi HY-2 Seersucker missiles used against targets in Kuwait were converted from anti-ship to land-attack missiles. But they could have been, and to much more lethal effect. Anti-ship systems like the HY-2 have a relatively easy task: using an autopilot, they fly over a relatively smooth plane (the ocean) and seek out a large metal object with a terminal guidance system.[13] By contrast, land-attack cruise missiles must navigate much more variegated terrain than anti-ship missiles before reaching their intended target while flying low to avoid detection. To get the missile there with great accuracy is much easier than it was a decade ago. Then, countries like the United States and Russia depended on tightly controlled guidance systems such as Terrain Contour Matching (TERCOM). Now, navigation for land-attack cruise missiles requires only relatively cheap inertial navigation systems (INS) integrated with Global Positioning System (GPS) receivers, both of which are readily available--separately or already integrated--as commercial off-the-shelf items. Had Iraq replaced the rudimentary autopilots that crudely guided the HY-2s it fired against Kuwait with modern land-attack navigation, their missile attacks against Kuwait not only could have avoided detection and interception but also produced militarily and politically significant damage.

The virtue of converting the HY-2 Seersucker into a land-attack missile lies primarily in its size. China is believed to have used the HY-4, which differs from its first cousin by employing a more modern turbojet engine, to develop a land-attack system.[14] The roominess and simplicity of design of the HY family of cruise missiles make transformation easier than were they smaller and more densely packed. Moreover, space freed up from removing old electronics, autopilot, and radar guidance allows for additional fuel, extending the missile's range.

Two main barriers stand in way of conversion. The first and most formidable challenge is providing a modern land-attack navigation system.[15] Although the component technologies and subsystems are available "off the shelf," it is not easy to integrate individually complex electronic subsystems into a working whole that achieves the consistently precise results demanded of a precision delivery system. At the same time, there are shortcuts. The most attractive is to acquire a commercially available UAV flight control system. Moreover, "system integration" software tools are readily available to assist in major elements of integrating modern flight management and control systems. The second and less formidable barrier is incorporating a suitable jet engine to replace the liquid fuelled rocket engine in the HY-2. Assuming China's willingness, the simplest course of action would be to acquire the Chinese HY-4 anti-ship cruise missile, which comes with the WP-11 turbojet engine. Barring that, there is a large pool of unrestricted turbojet engines in the civilian and military marketplace from Canadian, European, Japanese, U.S. and other international manufacturers. With space liberated from replacing the autopilot and radar guidance with a modern navigation system, a converted Seersucker cruise missile could achieve a range of at least 500 kilometers delivering a payload of 500 kilograms. That range could be extended even farther if the payload was reduced in exchange for more fuel, or if the airframe was extended by a meter to accommodate additional fuel.[16] Depending on the extent of any outside assistance, North Korea would require between three and ten years to convert the HY-2 into a land-attack cruise missile.[17]

Motivations to Acquire Land-Attack Cruise Missiles

Nothing in the current series of North Korean cruise missile testing indicates that Pyongyang has set out to accomplish such a transformation program. That said, such a program would be much more difficult to monitor than a ballistic missile development effort. The latter requires static testing of large liquid engines, which is significantly easier to detect than a land-attack cruise missile program hidden in aircraft development activity. Moreover, eventual testing of such a system would be accomplished over land, not sea, where detection is far more likely. The prospect of precision delivery of conventional payloads would not constitute sufficient motivation for North Korea to pursue such a transformation program, as the existence of a tested force of long-range ballistic missiles conveys more prestige and is a stronger deterrent to the United States and its regional allies than any number of regional-range cruise missiles. Nevertheless, as ballistic missile defenses become a more prominent feature of American and allied defense architectures, it would not be surprising to see countries like North Korea and Iran pursuing asymmetric means of delivering weapons of mass destruction--not as an alternative to ballistic missiles, but as a complementary means of taxing missile defenses.

The military motivations for doing so are compelling. Whether or not to allay the fear of Kuwaiti citizens, who have experienced several unnerving if ultimately harmless HY-2 Seersucker attacks since the first on March 20, coalition military officials have severely misrepresented the potential capability of these missiles. "The Seersucker is much, much smaller than a Scud and we don't think it can be converted to carry any significant NBC [nuclear, biological or chemical] payload," said one coalition officer after three Iraqi cruise missiles were launched from the Basra area into Kuwait on the evening of April 1.[18] True, the Iraqi modified Scud, called the al-Hussein, has a total weight of more than double the Seersucker's; however, each missile delivers a payload of 500 kilograms. Moreover, the Seersucker is a decidedly more suitable platform for delivering biological and chemical payloads than a Scud. The cruise missile's steady horizontal flight pattern permits release of the agent along a line of contamination, and enables the cruise missile to release and spray agent at right angles to the wind direction and upwind of the target area, greatly increasing dissemination efficiency.[19] Extensive modeling shows that cruise missile delivery of biological agents enlarges the effective lethal area of an attack by at least a factor of ten over ballistic missile delivery.[20]

The fact that a cruise missile's nominal range might be considerably shorter than a particular ballistic missile ought not to comfort defense planners. Traditional threat analyses employ "range rings" to demonstrate the distance beyond the launch point that a missile can reach. Cruise missiles render such calculations irrelevant. Because of their small size and ease of maintenance over long periods, cruise missiles are ideally suited as a "two-stage" means of delivery. They can be brought within range of their target and launched from freighters or commercial container ships.[21] In fact, a bipartisan panel assembled in 1996 to review the national intelligence estimate (NIE 95-19) on the ballistic missile threat to the United States concluded that not enough attention was being devoted to the possibility that land-attack cruise missiles could be launched from ships to threaten the U.S. homeland.[22] Alertness to such threats as alternatives to long-range ballistic missiles is now standard in annual national intelligence estimates.[23]

Missile Defense Complications

Should North Korea convert a portion of its existing arsenal of anti-ship cruise missiles into land-attack systems, it will complicate regional missile defenses. The presumption is that today's missile defenses could cope rather well with fairly primitive (defined as large and therefore assumed to be observable to radar) cruise missile threats. Patriot's lack of success against Iraq's low-flying cruise missiles in the current war suggests otherwise. Moreover, there is the problem of friendly-fire casualties. During the 1991 Gulf War, coalition forces practiced highly restrictive rules of engagement. Because the allied air forces had essentially eliminated Iraq's aircraft threat, its missile defenses could train their radars on Iraq's Scud missiles, meaning radars could focus on high-angle missile trajectories and not have to worry about low-flying threats. Thus, the probability was low that friendly aircraft returning to base might be confused with enemy threats and inadvertently shot down.

While Patriot missile batteries in the 1991 Gulf War proved much less successful than initial claims suggested, highly restrictive rules of engagement eliminated friendly aircraft from being shot down. Unfortunately, the current campaign against Iraq has not avoided this risk. An American Patriot missile inadvertently shot down a British Tornado fighter two days into the war. The very next day--no doubt in order to avoid the same fate as the Tornado--a U.S. Air Force F-16 destroyed a Patriot ground-based radar after it inadvertently "painted" the F-16.[24] Preliminary reporting indicates that Patriot missile batteries did enjoy almost a 50 percent rate of success against ballistic missiles.[25] But concerns about Iraq's possible use of low-flying UAVs armed with chemical or biological agents probably also led coalition planners to loosen the rules of engagement practiced in 1991, such that Patriot radars were forced to distinguish between friendly returning aircraft and low-flying Iraqi threats. Unfortunately, they did not always succeed. Iraq's surprising use of Seersucker cruise missiles beginning on the first day of the war probably only complicated matters further. Peacetime simulations of air campaigns (without restrictive rules of engagement) typically examined in joint U.S. military exercises routinely produce unacceptable levels of friendly-fire incidents.[26]

There are ways to reduce such friendly fire incidents, which will become all the more necessary if the cruise missile threat blossoms. Improved seekers for surface-to-air missiles like Patriot would enhance performance against low-flying missiles. A more comprehensive solution would be a common air picture with the assured capacity to distinguish between friendly aircraft and enemy cruise missiles. This requires the merging of various service and Missile Defense Agency battle management command, control and communications programs to achieve interconnectivity among a disparate array of service sensors and weapon systems. The quest for such interconnectivity--now known as the Single Integrated Air Picture (SIAP)--was initiated in 1969 in attempts to improve tactical air control.[27] But the advent of the cruise missile threat makes the task more urgent than ever, as demonstrated by events over the last two weeks along the border between Kuwait and Iraq.

Implications for Japan

As Japan moves closer to making a decision about missile defenses, it should refrain from dismissing North Korea's test firings of anti-ship cruise missiles as incapable of threatening Japan. Events in the Middle East show that low-flying cruise missiles present unique challenges for missile defenses. If North Korea were to convert some of its inventory of HY-2 cruise missiles (or acquire HY-4s from China), they could conceivably extend the range (by reducing payload) to reach Japanese targets. Even without such range extension, cruise missiles could be delivered from freighters.[28] Moreover, the justification for missile defenses should be country neutral. North Korea is not the only conceivable long-term threat to Japanese interests upon which the expenditure of substantial funds should depend. Cruise missiles are likely to figure increasingly into the many nations' defense plans due to their relatively low cost and the improving capacity of the United States and its regional partners to defend against ballistic missiles.

Equally imperative are diplomatic efforts to forestall the emergence of the cruise missile and armed UAV threat. Japanese nonproliferation specialists should examine closely and engage vigorously in supporting various proposals currently under consideration in the Missile Technology Control Regime and the Wassenaar Arrangement.[29] These proposals are designed to tighten controls on cruise missiles, UAVs, and critical supporting technologies. In the end, hedging against the cruise missile threat depends as much on developing more effective nonproliferation policies as it does on planning for more versatile missile defenses.


[1] Peter Baker and Susan B. Glasser, "Iraq Fires Missiles Toward Kuwait," Washington Post, March 21, 2003, p. A21.
[2] "Missile Fired at Kuwait City; Explosion Rocks Shopping Mall," Associated Press, March 28, 2003 at http://www.washingtonpost.com.
[3] Tim Butcher, "Iraq's missile is a damp squib," Daily Telegraph, 2 April 2003 at http://www.telegraphi.co.uk/news/main.jhtml?xml=%Fnews%2F2003%F04%F02%Fwtim02.xml.
[4] Besides the new ROK president's inauguration, Jane's special correspondent Joseph S. Bermudez reasonably speculates that U.S. Secretary of State Colin Powell's visit to the region to deal with the continuing nuclear standoff with North Korea, as well as North Korean leader Kim Jong-Il recent birthday celebration, may also have affected the timing of the February tests. See Joseph S. Bermudez, "North Korea tests anti-ship cruise missiles," Jane's Defence Weekly, at http://www.janes.com/security/international_security/news/jdw/jdw030228_1_n.shtml.
[5] A point made by my Center for Nonproliferation Studies colleague Dr. Phillip Saunders.
[6] For useful background on the origins of these anti-ship cruise missiles, see Duncan Lennox, ed., "China: Offensive Weapons," Jane's Strategic Weapon Systems (Surrey, United Kingdom: Jane's Information Group, Ltd., 1995).
[7] For technical details on Chinese anti-ship cruise missiles, see http://www.sinodefence.com.
[8] Michael R. Gordon, "North Korea Tests Cruise Missile Designed to Sink Ships," New York Times, 1 June 1994, p. A12.
[9] The best account of these tests is furnished in Bermudez, "North Korea tests anti-ship cruise missiles."
[10] Bermudez reports that the February 24 test included two cruise missiles, one of which failed while the other flew to a distance of 60 kilometers. Anonymous South Korean defense officials believe that the March 10 test was a failure. See "ROK Defense Official: DPRK 10 Mar Missile Test-Firing 'Believed to Have Failed'," KPP200303180000071 Seoul Yonhap in English, 18 March 2003 [FBIS Transcribed Text]. Details are lacking on the April 1 test. See "Officials: N. Korea Test-Fires Missile," Associated Press, April 1, 2003, at http://news.findlaw.com/ap_stories/i/1104/3-31-2003/20030331224501_06.html.
[11] Ibid.
[12] For more on these and other cruise missile developments, see Dennis M. Gormley, Dealing with the Threat of Cruise Missiles, Adelphi Paper 339 (Oxford: Oxford University Press for IISS, 2001), passim.
[13] In the case of the radar-guided HY-2, the guidance system homes in on the target during the last 10 kilometers of flight. One press report indicates that the Iraqi launches avoided using their terminal radars to reduce their already small chance of detection. Butcher, "Iraq's missile is a damp squib."
[14] Steven J. Zaloga, "The Cruise Missile Threat: Exaggerated or Premature?" Jane's Intelligence Review (April 2000), pp. 47-51.
[15] For a description of the technical challenge of producing a modern land-attack navigation system, see Gormley, Dealing with the Threat of Cruise Missiles, pp. 30-33.
[16] This analysis benefited greatly from the assistance of Dr. Gregory DeSantis.
[17] The shorter figure assumes significant outside assistance, including experienced engineering support and the provision of production equipment. The longer figure assumes an essentially indigenous effort. These estimates also include time needed to achieve some modest level of overall system reliability, maintainability, and logistical support, as well as integration into a user force structure. Were the criteria for system availability simply a matter of completing one successful test launch, an initial operational capability could be reached in less time.
[18] Butcher, "Iraq's missile is a damp squib."
[19] See Edward Eitzen, "Chapter 20 -- Use of Bio Weapons," in Medical Aspects of Chemical and Biological Warfare (Washington, DC: Walter Reed Army Medical Center, 1997), pp. 440-442.
[20] Dennis M. Gormley, "Hedging Against the Cruise-Missile Threat," Survival, vol. 40, no. 1 (Spring 1998), pp. 95-96. Unless Iraq managed to develop a greatly improved means of disseminating chemical or biological agents via ballistic-missile delivery, it seems likely that any residual al-Hussein missiles contain within the warhead a stainless steel container for biological agents and an aluminum container for chemical agents, with a capacity of about 145 liters of liquid agent. On impact with the ground, the warhead would detonate, disseminating the agent by means of explosive force. Such a crude method of dissemination would destroy perhaps 90% of a biological agent, meaning less than 15 liters would remain to contaminate an area of probably a few hundred meters in diameter. See Dennis M. Gormley (unsigned), "Defending against Iraqi missiles," IISS Strategic Comments, vol. 8, issue 8 (October 2002).
[21] To be sure, short-range ballistic missiles can also be delivered using a two-stage means of delivery. However, the overall process is much more complex and logistically demanding, especially if covertness is sought.
[22] "Intel Official Defends Threat Estimate," Inside Missile Defense, vol. 2, no. 25, December 11, 1996, pp. 1, 10-14.
[23] See, for example, "Missile Developments and the Ballistic Missile Threat Through 2015," Unclassified Summary of a U.S. National Intelligence Estimate approved for publication on January 10, 2002, Central Intelligence Agency, Washington, DC. Available at http://www.cia.gov/nic/pubs/other_products/Unclassifiedballisticmissilefinal.htm.
[24] On the Tornado incident, see Vernon Loeb, "Patriot Downs RAF Fighter," Washington Post, March 24, 2003, p. A20 and "Friendly Fire: How it can happen," BBC On-Line, March 23, 2003, at http://news.bbc.co.uk/go/pr/fr/-/2/hi/uk_news/2878113.stm.
[25] Alex Stone, "Patriot Games," The New Republic On-Line, 2 April 2003, available at http://www.tnr.com.
[26] Gormley, Dealing with the Threat of Cruise Missiles, pp. 61-62.
[27] For more on SIAP and other challenges of defending against cruise missiles, see Gormley, Dealing with the Threat of Cruise Missiles, Chapter 4.
[28] Japanese officials have also complained about regular intrusions into Japans exclusive economic zone by Chinese and North Korean ocean survey and intelligence collections ships. The Japanese Coast Guard intercepted and sank one suspected North Korean spy ship on December 22, 2001 after an exchange of missile and machine gun fire.
[29] For a recent analysis of the state of these nonproliferation efforts, see Dennis M. Gormley and Richard Speier, "Controlling Unmanned Air Vehicles: New Challenges," a paper sponsored by the Non-proliferation Education Center, March 17, 2003 (Available from the author upon request). Also see Gormley, Dealing with the Threat of Cruise Missiles, Chapter 5.


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Author(s): Dennis Gormley
Related Resources: Missile, N. Korea, Iraq, East Asia, Middle East, Weekly Story
Date Created: April 8, 2003
Date Updated: -NA-
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