Ground-Based Midcourse Defense Against ICBMsHere is an excerpt of a feature article on the Ground-Based Midcourse Defense (GMD) system from eDefense Online. For a brief description of the GMD, see this earlier post on Situational Awareness.
During the Cold War, the Soviet Union's arsenal of thousands of land-based intercontinental ballistic missiles (ICBMs) and submarine-launched balistic missiles (SLMBs) – not to mention nuclear weapons deliverable by strategic bombers and shorter-range systems – was countered by the equally impressive collective arsenals of the US, the UK, and France. It is easy to forget – even easier to lampoon – the state of affairs that dominated superpower politics in the last three decades of the 20th century, with its missile gaps, fail-safe points, duck-and-cover drills, and backyard fallout shelters. Yet it is clear today that decision-makers on both sides of the Iron Curtain understood that any general war would quickly go nuclear and, hence, to oblivion. The only question, really, was how to go about it. Do you launch on warning or ride out the attack? Do you employ massive retaliation or flexible response? Those missile-defense systems allowed at the time under the terms of the Anti-Ballistic Missile (ABM) Treaty were skeletal at best. Bombs would have bounced the rubble on both sides. This understanding, exemplified in the doctrine of Mutually Assured Destruction (MAD), is widely regarded as having kept the peace.
There is a fear today that a rogue state possessing both nuclear weapons and the means to deliver them might be undeterrable. This is an amazing concept, really. Imagine a power so careless of its own survival that it would commit suicide by launching an ICBM at the greatest power on Earth, one that could and quite possibly would destroy the offending regime, if not the nation. Yet preventing an enemy from taking such action against the US at some point in the near future is the key mission of the US Missile Defense Agency (MDA). In fact, the US government considers the threat of North Korea lashing out in its death throes with a nuclear strike to be so real that the "urgent need" for a National Missile Defense (NMD) system required the high-risk, high-cost development tempo of the program.
Since 1985, about $90 billion has been spent on missile defense by the US under various programs, beginning with the Reagan-era Strategic Defense Initiative (SDI) through the Clinton administration's Ballistic Missile Defense Organization and into today's Missile Defense Agency. But funding since fiscal year 2001, at $4.8 billion, has been stepped up quite a bit, with $7.8 billion in FY02, $7.4 billion in FY03, $7.7 billion in FY04, and $9 billion in FY05. Missile defense accounts for about 2% of the Defense Department budget, more than any other program. Ground-Based Midcourse Defense (GMD) is only one facet of the expenditure. Other important activities include the Boeing Airborne Laser (ABL), Lockheed Martin Aegis Ballistic Missile Defense, and the Northrop Grumman Kinetic Energy Interceptor (KEI) programs. Each of these programs and attending technologies address different aspects of the ballistic-missile threat. The MDA views the entire package, including GMD, as an integrated, multi-phase effort to develop and deploy a defense network capable of covering the US and allied nations from the full range of ballistic-missile threats.
Urgent Need, High Risk
For all intents and purposes, the GMD system, as it is currently configured, is designed to handle one contingency: an "end-game" launch of an ICBM from North Korea, possibly during the dust-up of a regime collapse. This problem has been weighing on the minds of defense planners for more than a decade, since the latter years of President Kim Il Sung's rule. The instigation of this concern was an assessment that North Korea was determined to develop and deploy nuclear weapons and ballistic missiles to deliver them, apparently confirmed when North Korea declared its intent to withdraw from the Nuclear Non-Proliferation Treaty in 1993. Extended brinksmanship ensued. During this time, North Korean bellicosity was generally viewed as coercive in nature, that playing the "nuclear card" would enable the regime to achieve leverage in its dealings with the US and its allies, especially South Korea and Japan.
The resurgence of National Missile Defense as we know it took shape after the US Department of Defense (DoD) announced the so-called "three-plus-three" plan in 1997, under which a decision would be made in 2000 about whether the threat warranted a fast-track deployment of a GMD system in 2003 or if deployment could be deferred. Extended domestic politics ensued. Ultimately, the DoD decided that the threat posed by North Korea did indeed justify a rushed deployment of a rudimentary NMD capability. This decision did not come without attending costs and risks. In fact, a NMD review committee chaired by General Larry Welch, USAF (ret.), a former Air Force chief of staff, concluded that the risks were such that an initial operational capability (IOC) in 2003 was unattainable. Scheduled IOC was put off until 2005.
The phased deployment of the GMD segment of the NMD system envisioned a series of threat levels that could be matched over time with ever-increasing capability. The so-called C1 threat level of a strike from North Korea using up to five single-warhead ICBMs that dispense few if any countermeasures would be countered by a system very much like the one now in place. The C2 threat level projected a reasonably orchestrated strike from East Asia or the Middle East involving a dozen or more sophisticated ICBMs equipped with countermeasures. This threat would require 100 or so Ground-Based Interceptor missiles, an expanded early-warning radar network, and a new-generation satellite-based Space Tracking and Surveillance System (STSS). Original estimates for this capability achieving operational status were 2010, but this has been pushed back to 2012 at the earliest. Projections of more advanced threat levels exist, but since these involve ICBM strike capabilities possessed by Russia and those under development by China, there is not much detail available on what the NMD architecture to counter them would look like or when it might be deployed.
In fact, one of the challenges to NMD had been the diplomatic one. First of all, there was the ABM Treaty to be withdrawn from, since many of the technologies required for strategic ballistic-missile defense were banned under it. But this was accomplished with surprisingly little shoe-banging from Russia in 2002, despite apocalyptic predictions from critics. Subsequently, the US has taken pains to assure Russia and even China – which was not a party to the ABM Treaty – that NMD is not intended to counter their strike capabilities. The assumption, strategically, is that the time-proven concept of deterrence will continue to keep the peace with both nations, at least with regard to nuclear war. From a practical standpoint, Russia appears confident that it will remain able to overwhelm or evade any NMD system the US deploys, and the latest generation of Russian ICBMs, the Topol-M, bears this out. China, which is understood to have only a limited number of true ICBMs capable of striking the continental US, has reasons to be more suspicious of US intentions with regard to NMD. Certainly, a bubbling disagreement over the status of Taiwan (see "Flashpoint Taiwan Straits") runs the risk of open conflict between the US and China. A 1999 Rand report entitled "Planning a Ballistic Missile Defense System of Systems: An Adaptive Strategy" pointed out that managing the objections of China would be an important component to deploying NMD.
Leaving aside diplomatic issues, there are real technical challenges to deploying a robust NMD capability. The Rand report put it this way:
"Even under ideal circumstances and with the latest technologies, ballistic-missile defense is exceedingly difficult. Destroying an RV [reentry vehicle] in flight requires an end-to-end sequence of successful tasks: detecting and classifying the threat missile, predicting the threat trajectory, cueing sensors down the line, tracking the target, discriminating the target from clutter and countermeasures, acquiring the target for intercept, intercept, kill assessment, and repeating the sequence as required. A failure anywhere in this chain precludes successful intercept."
Physics, Not Political Science
ICBMs go through a number of phases from launch to when payload warheads detonate over the target. The launch proceeds from the boost phase of approximately 90 to 300 seconds, during which the missile's series of booster stages ignite, burn, and fall away. All the while, the missile accelerates into the midcourse phase, lasting up to 20 minutes, in which the payload complex arcs out of the atmosphere on a suborbital trajectory. During the midcourse portion of the flight, the payload complex may release decoys and could possibly maneuver using attitude-control thrusters. The warhead or warheads are released during this phase. In the terminal phase, lasting perhaps 30 seconds, the warheads reenter the atmosphere and fall toward their targets. Shorter-range ballistic missiles go through the same stages, but of shorter duration.
Each phase has its own program to develop "interceptors" that would intercept and eliminate the enemy missile. Addressing the boost phase, the Airborne Laser system would consist of aircraft that fly about in shifts, all day and every day, ready to shoot down ballistic missiles using a chemical-oxygen-iodine laser, the heat of which would cause the ballistic missile to explode or at least leak so that resultant change in pressure causes the missile to go off course. There is also the Kinetic Energy Interceptor (KEI) under development that would be able to engage ballistic missiles in their boost phase with very fast interceptor missiles from either land- or ship-based launchers deployed in theater. For the mid-course phase, the GMD system, as outlined above, would swing into action.
In addition, apart from the threat of intercontinental ballistic missiles, still other programs are being developed to intercept short- or medium-range ballistic missiles, including Scud missiles, which Iraq was known to lob on Israel and US forces during Operation Desert Storm. These interception systems include the Patriot Advanced Capability-3/Medium Extended Air Defense System (PAC-3/MEADS), the Arrow 2 missile-defense system deployed by Israel, and the ship-based Aegis Ballistic Missile Defense system using the SM-3 missile. All of these missile-based interceptor technologies employ "hit-to-kill" kinetic warheads.
These various forms of interception will need a lot of help to hit their targets, particularly the long-range ballistic missiles. A number of supporting systems are in development to sense these incoming missiles and guide the interceptors to them. The Forward-Based X-band Radar Transportable program, for instance, would use solid-state, phased-array antennas to watch out for and track intercontinental ballistic missiles and medium-range threats. The Space Surveillance and Tracking System, along with the Space-Based Infrared System-High (SBIRS-H) program, would also be able to detect and track missiles from their launch to midcourse flight but, instead of using X-band radar, would use visible and infrared sensors. The Aegis system, in addition to having its own SM-3 interceptors, would also provide long-range surveillance and tracking of threats. These various means of tracking threats would be overseen and controlled by the Command and Control, Battle Management, and Communications element of the program. Information from the various surveillance systems could be correlated and passed along to the different types of interceptors, with the battle-management system used to make decisions about how to respond to threats.
Proponents of GMD technology, and particularly the contractors, focus on the capability and reliability of the key technologies. The sensor systems on the DSP satellites have a long track record of reliability. Similarly, the Aegis Ballistic Missile Defense system has successfully detected, tracked, and engaged missile targets in numerous tests. Likewise, the various phased-array radar systems that will be used for early warning and tracking of ballistic missiles have been shown to be effective and reliable. Perhaps most importantly, though, the hit-to-kill concept employed by the various kinetic kill vehicles under development for the NMD program has been demonstrated in suborbital- and terminal-engagement live-fire tests. Moreover, target-discrimination technology that fuses data from radar and EO sensors has been shown to be successful in picking warheads out from attending decoys and debris. It is their ability to demonstrate these key capabilities that is the source of much of the confidence expressed in the NMD system by officials at the MDA and its top contractors.
In all of these tests, the testers knew ahead of time where the target missiles were coming from and when they would be launched. Knowing ahead of time where and when a target is going to be makes tracking that target much easier than having no advanced notice, as might expected to be the case in an actual missile attack. Apart from criticizing the nature of the testing so far – at least to the extent that the unrealistic conditions surrounding the tests mean that statements about the system's effectiveness at this point can only be conjecture – critics also point to the use of certain types of countermeasures by enemy missile designers that could stymie the missile-defense system. These include the use of radar-absorbent materials (RAM) on the surfaces of the enemy missiles that would make them hard to detect by the interceptor sensors, as well as the use of advanced decoys to throw the interceptor off its scent.
Frankly, defeating advanced decoys and countermeasures is not in the cards for the C1 implementation of GMD. The North Koreans do not yet have a demonstrated ICBM capability, let alone the expertise to incorporate advanced countermeasures technologies into their systems. Many of the criticisms leveled at NMD – and the GMD segment in particular – about its inability to handle multiple decoys and advanced countermeasures or launches from unexpected quarters of the globe are unfair, in that such threats are not expected as imminent. The C1 implementation of GMD is a point defense against a very specific potential enemy at a particular moment in time. Everything points at North Korea. As the threat evolves, NMD will be upgraded accordingly. Charles LaDue, director of advanced missile-defense directed-energy weapons at Raytheon Missile Systems (Tucson, AZ), called this a capabilities-based approach. "The goal is to build up capabilities and deploy them to stay ahead of what the enemy can do," he said.
However, mundane problems can sometimes overshadow the greatest technological achievements. Even though the tests done to date have been quite controlled, based on advanced knowledge of the locations of objects to be tracked and targeted, not all of the tests done so far have been successful. Of the 10 times the GMD has been tested, for instance, it has successfully intercepted an incoming missile five times, with the most recent successful test in 2002, noted Victoria Samson, a research analyst with the Washington, DC-based Center for Defense Information (CDI) research group. It is important to note that all of these interception tests were done with kinetic-kill vehicles launched from modified Minuteman missiles as opposed to the GMI rocket, which is undergoing a separate test series.
Cooling problems in the EKV's EO sensor, faulty signals between the booster rocket and the payload, and faulty components in the EKV's separation mechanism have all caused test failures. The possibility of such low-tech failures compromising a missile-defense test, let alone a live interception under wartime pressures, is a real worry. The highly complex GMD system, which requires an extended chain of events to occur flawlessly in order to achieve an intercept, has had a comparatively spare testing regimen. One potentially encouraging aspect of the testing program has been periodic failures in getting decoys to inflate. Perhaps the North Koreans will have this problem, too.
A 1998 Welch Panel report pointed out that one of the vulnerabilities in the high-risk development track of the GMD program was that it would be "hardware poor," meaning that there would be little, if any, prototyping and that articles would fly as built. The report concluded: "Due to the inability to perform end-to-end tests in a realistic environment, simulation and analyses will provide much of the necessary design and decision information."
Despite not having completed testing of the various components, the MDA in 2004 began deploying ground-based missile interceptors in Alaska, at the behest of the Bush administration, which wanted to achieve its promised goal of having some type of missile-defense capability ready by the end of 2004, even if limited (see "Early Deployment of Missile Defense"). Thus, the first ground-based missile interceptor was planted at Ft. Greely, AK, on July 22, 2004. The SBX was originally scheduled to be in place by October 2005. It did perform a 58-day shakedown cruise in the Gulf of Mexico that ended that month (the 282-foot-high, 50,000-tons ocean-going structure was obliged to dodge Hurricanes Katrina and Rita), but it will be several more months until the SBX reaches its homeport of Adak Island, AK.
Tests of other NMD elements are proceeding apace. The Forward-Based Transportable X-Band Radar and an Aegis ship were tested in September to track a US Air Force missile originating from Vandenberg AFB, with their tracking information passed along to the command-and-control system. The Sea-Based X-Band radar transmitted a radar beam for the first time last Sept. 11. Also, a series of tests of the Airborne Laser's battle-management system and fire-control radar were completed this summer (see "Testing Continues on USAF Airborne Laser").
Complaining about critics who characterize the system as untested or unproven, and expressing the wish that "more people would give us the benefit of the doubt," MDA Director Lt. Gen. Henry Obering in an interview in the November issue of Arms Control Today declined to discuss in detail the likely current effectiveness of the system, saying that information is classified but calling it "much better than zero." The system cannot handle a "complex threat suite," he said, but it can handle what the MDA believes is the likely existing threat, adding that the recent unsuccessful tests of the GBI do not indicate the system's lack of functionality but were simply "technical glitches."
The Bush administration and the MDA, while noting that the missile-defense system is a work in progress, say that an initial capability for the system already exists. But at the same time, it has not been declared operational by the US military. This points to what some observers see as essentially inaccurate statements about the system's current capability. Though not tested as a system under realistic conditions – that is, without the system having any prior knowledge of the time of the enemy missile's launch, its location, or its trajectory – the MDA and members of the Bush administration nevertheless say the program provides a "limited capability." It would not be able to stop barrage of missiles that a country like China or Russia would be able to launch, but then again, it's not intended to. This harkens back to the "high confidence" expressed that the system could, right now, defeat a one-off, two-off attack from North Korea. This was the urgent need, and this is the capability as advertised.
The unofficial motto of the NMD program is "Engage early, engage often." Building on the initial GMD capability, the US plans to deploy a series of systems that will enable this motto to be put into practice. Ultimately, the purpose of NMD is to loosen constraints on US national-security policy by reducing or even eliminating the capacity of certain nations to threaten a nuclear attack. But in order to for NMD to achieve this, it will have to be widely perceived as effective. The US is only at the initial stage of demonstrating the effectiveness of such a system. But the security-policy implications of it are already being calculated around the world.