2013-04-07 by Richard Weitz
The Barack Obama administration’s missile defense policy presents both elements of change and continuity with the plans set out by the previous George W. Bush presidency.
The main change is that the administration has deemphasized near-term efforts to develop and apply revolutionary BMD technologies and instead has sought to build, in an evolutionary manner, on proven existing technologies such as the Patriot system for terminal phase defense and the Aegis/Standard Missile combination of the U.S. Navy for mid-course intercepts.
This change reflects technology and funding constraints as well as the evolving nature of the missile threat facing the United States and its allies.
Of the six main BMD programs the Obama administration inherited from its predecessor, the Obama administration has expanded some and recast or cut others. It cancelled the Kinetic Energy Interceptor program due to high costs and the Airborne Laser program in February 2012 due to cost and technological challenges. The United States is no longer planning to develop directed energy weapons using lasers to heat the metal skin of a long-range ballistic missile until it ruptures and disintegrates.
But some systems are being developed that can use lasers against UAVs and cruise missiles, so the technology might evolve in coming years to address these longer-range missiles—though any laser would have to be either located close to the launch site of the missile or in outer space.
In contrast, the Obama administration has expanded the Aegis SM-3 system to make it the main BMD efforts, especially for intercepting long-range ballistic missiles in their mid-course phase.
The United States currently lacks an operational early interceptor for attacking a missile in its boost or ascent phase (when the rocket has ceased burning but the missile is still gaining altitude). Previous attempts to build early interceptors failed because of their immature technologies, impractical operational concepts, and exorbitant costs. Advances in UAV technologies have led some people to consider developing a high-speed, two-stage, hit-to-kill interceptor missile, launched from a high-altitude long-endurance UAV. But for now the main protection of the U.S. homeland from missile attack comes from the GBI and Aegis SM-3 systems.
The Obama administration is continuing the deployment of Ground-Based Mid-Course Interceptors (GBIs) in Fort Greely, Alaska, and Vandenberg Air Force Base, California. These are intended to defend the continental United States from missiles launched from North Korea or Iran.
This GBI system will continue to rely on four fixed radar facilities at Shemya, Alaska; Beale Air Force Base, California; Fylingdales in the United Kingdom; and Thule, Greenland. The network also includes mobile ground- and sea-based X-band radars. These X-Band radars can detect ballistic missiles early after their launch and provide accurate tracking and discrimination information, increasing the chance of intercepting the missile. The AN/TPY-2 radars provide expanded and overlapping sensor coverage, and can help discriminate between the warhead and false targets. These radars work best when integrated into a wider network that includes space-based sensors on satellites.
The MDA has recently resumed flight testing of the Ground-Based Mid-Course Interceptor (GBI) in January 2013, following a failed intercept test in December 2010.
The current GBI is a three-stage, solid-fuelled booster with an Exo-atmospheric Kill Vehicle (EKV) that uses the kinetic energy from colliding with the re-entry vehicle to destroy it. The GBI’s booster rocket carries the EKV toward the target’s predicted location in space. Once released from the booster, the EKV uses guidance transmitted to it and from its own on-board sensors to collide with the target above the Earth’s atmosphere.
The GBI also has redundant fire control nodes, interceptor launch facilities, and a communications network. GMD Fire Control receives data from satellites and ground-based radar sources and uses that data to support GBI interception of the targets. The GFC also provides the Command & Control, Battle Management & Communications element with data for situational awareness. Plans to develop a two-stage GBI exist but have not been implemented.
The other mid-course interceptor is the Navy’s Aegis-SM3 combination, which builds on the Aegis Weapon System, the Standard Missile, and the Navy and Joint Forces Command, Control and Communication systems. In terms of regional defense, Aegis BMD can defeat short-to intermediate-range, unitary and separating, midcourse-phase ballistic missile threats as well as short-range ballistic missiles in the terminal phase. The SM-3 intercepts ballistic missiles above the atmosphere in their midcourse phase of flight using a “hit- to-kill” collision in which the warhead is destroyed through kinetic energy.
The MDA and Navy plans call for fielding increasingly capable versions of the SM-3 in coming years.
The current version, the SM-3 Block IA, is the first widely operational U.S. mid-course ballistic missile defense interceptor. It is now being complemented by the more capable SM-3 Block IB, which can better discriminate and target the warhead despite adversary debris and countermeasures. It boasts an improved 2-color target seeker, advanced signal processor, and a superior control system for adjusting its course.
In February 2013, the Navy intercepted a medium-range ballistic missile using an already operational SM-Block IA interceptor and trafficking data from a remote Raytheon senor payload on the Space Tracking and Surveillance System-Demonstrator (STSS-D) satellites. The interceptor test confirmed that, even as the United States develops and deploys more advanced versions of the SM-3, the existing systems can still play a key role in U.S. and allied missile defenses. It also demonstrated how using the STSS-D satellites can allow the Navy to expand its battlefield sensor capabilities beyond those organic to a ship’s radar.
The BMD ships can detect the path of a missile from greater distances and use the radar to refine its tracking and interception calculations. It also gives the Navy greater flexibility in coordinating its BMD ship and battle plans. Since the SM-3 block 1A and SM-3 block 1B missiles are similar in design, the SM-3 1B should also be able to draw on the STSS-D data.
In contrast to the Block IA and 1B versions, which have a 21-inch-diameter booster stage at the bottom but are 13.5 inches in diameter along the remainder of their lengths, the SM-3 Block IIA version will have a 21-inch diameter along its entire length. The increase in diameter to a uniform 21 inches provides more room for rocket fuel, permitting the Block IIA version to achieve a greater maximum velocity, a longer flight, and cover a larger area than that of the Block IA and IB versions. It can also carry a larger-diameter kinetic warhead. The initial SM-3 Block IIA flight test is scheduled for 2015, with a transition for full production around 2018.
The United States and Japan have cooperated in developing certain technologies for the Block IIA version, with Japan funding a significant share of the effort.
Besides its expected deployment on U.S. and Japanese warships, the United States plans to place some of the Block IIA ashore on Poland and perhaps elsewhere. An Aegis Ashore battery will strongly resemble the top half of an Aegis warship.
Aegis radar’s role in missile defense has evolved as its capabilities have improved. The U.S. Navy began the development of the Aegis combat system more than 30 years ago by integrating advanced radar and signals capabilities with a variety of guided missiles deployed on cruisers and destroyers in order to defend aircraft carriers and their battle groups. In the initial fielding of the BMDS in 2004, Aegis BMD’s role was that of a forward sensor. Aegis BMD ships were forward deployed to extend the battlespace, provide early warning of an ICBM launch, and transmit track data to the Ground-based Missile Defense command center.
In 2005, Aegis BMD’s role evolved to include an engagement capability. Aegis BMD ships, armed with the SM-3 Block IA, proved capable of intercepting short- to intermediate-range ballistic missiles in the midcourse phase of flight. The Aegis BMD engagement capabilities expanded to include the terminal capability in 2006.
The Aegis BMD 3.6.1 configuration (midcourse and terminal engagement capabilities) is presently deployed throughout the Aegis BMD Fleet.
The upgraded BMD 4.0.1 improves target discrimination, enhances target tracking, and allows for longer-range engagements. It offers exo-atmospheric engagement capability against short-, medium-, and some intermediate-range ballistic missiles using the SM-3 Block IA missile and can also provide better support for later SM-3 interceptor versions. These Aegis radars generate tracking data to cue other missile defense sensors and provide the fire control data to GBIs located in Alaska and California. They also cue other BMD systems including THAAD, PAC-3, and other Navy BMD ships.
There are now more than two dozen Aegis BMD combatants in the U.S. Navy, mostly destroyers but also some cruisers. About twice as many of these ships are assigned to the U.S. Pacific Fleet than with the Atlantic Fleet. In response to the increasing demand for Aegis BMD capability from the Combatant Commanders, the MDA and Navy are working together to increase the number of Aegis BMD capable ships.
Such efforts consist of upgrading Aegis destroyers to the BMD capability, incorporating Aegis BMD into the Aegis Modernization Program and new construction of Aegis BMD destroyers. By 2018, there will be more than 30 BMD capable Aegis ships, using all four versions of the Aegis system.
Aegis BMD also provides Sea-Based Terminal defense capability using modified SM-2 Block IV missiles to engage short-range ballistic missiles in the terminal phase. The Standard Missile-2 Block IV (SM-2 Block IV) is designed to intercept shorter-range ballistic missiles inside the atmosphere during their terminal phase of flight. It is equipped with a blast fragmentation warhead. The SM-2 Block IV will be replaced by a BMD version of the new SM-6 interceptor.
The United States currently has two terminal phase land-based interceptors.
The Patriot Advanced Capability-3 (PAC-3) Missile Interceptor Batteries, which is fielded by the U.S. Army and many U.S. partners, is a more mature if less capable terminal interceptor. It builds on the proven Patriot air and missile defense infrastructure. PAC-3 provides simultaneous air and missile defense capabilities as the Lower Tier element in defense of U.S. deployed forces and allies.
The PAC-3 include interceptor missiles, launchers, radars, an engagement control station, a power plant, and other elements. They are designed to attack hostile aircraft, tactical ballistic missiles, cruise missiles and UAVs. Each battery has 16 PAC-3 interceptors, each of which can be fired individually. Each interceptor missile weighs 340 kg and flies at 5,000 km/h. The interceptor has a range of 100 miles (160km), and can reach altitudes of about 80,000 feet.
Combined with the high accuracy of their radar sensors and targeting systems, the PAC-3 contributes to the entire BMDS’ situational awareness by transmitting precision cueing data to other theater elements while simultaneously protecting system assets against short-range ballistic missiles, large-caliber rockets, and air-breathing threats.
For homeland defense, PATRIOT provides detection, track, and engagement of short-range ballistic missiles and cruise missiles. It has added Upper-Tier Debris Mitigation Capability to reduce the negative impact of excessive radar load and potential missile waste caused by debris from upper-tier intercepts. The Army is responsible for production and further development of the PAC-3, while the MDA remains responsible for the BMDS and PAC-3 interoperability and integration efforts.
The PAC-3 can work with the Terminal High Altitude Area Defense (THAAD) system under development, which can intercepts short and medium range missiles in their terminal phase using a hit-to-kill approach.
It presently is the only interceptor in the U.S. inventory with the operational flexibility to intercept missiles both inside and outside of Earth’s atmosphere. The high-altitude intercept mitigates effects of enemy weapons of mass destruction before they reach the ground.
THAAD aims to provide an integrated, overlapping defense against missile threats in the terminal phase of flight by forming a multi-tier theater defense using peer-to-peer engagement coordination, early warning track data, and battle management situational awareness.
A THAAD Battery consists of four main components.
- First is the launcher, which is truck-mounted, highly mobile, and able to be stored.
- Second are the interceptors, with eight per launcher.
- The third component is the Radar, which consists of a X-band radar which searches, tracks, and discriminates objects and provides updated tracking data to the interceptor.
- The Fire Control system, the last component, is the communication and data-management backbone. It links THAAD components together as well as to external Command and Control nodes and to the entire BMDS.
The first THAAD battery was activated in 2008, the second activated a year later. The MDA hopes the third and fourth batteries will be fielded in the next two years. THAAD is undergoing extensive additional testing after a series of test failures led to its being completely redesigned in 2005. When the SM-3 moves ashore and becomes a more powerful ground-launched variant, it might provide the same high-altitude capabilities as THAAD but with more reliability.
Editor’s Note: Leveraging the near term and not funding the long term is not a prescription for success in the mid term. Imagine if the Reagan era investments had not been made to provide the current Administration with options? In a Korean crisis in 15 years, what options are Obama-era investments providing for that future Administration?