feature article

March 2007

Sea-Based Missile Defense Scores Hits, But Will it Work in a Real Attack?

By Sandra I. Erwin

The Navy has embarked on a plan to deploy 18 warships that would defend the United States and key allies against ballistic missile attacks. But there is still one major weakness in U.S. missile defense systems that neither the Navy nor the Pentagon’s Missile Defense Agency has yet been able to overcome — their ability to discern real warheads from harmless decoys.

Since the end of the Cold War, the Defense Department has spent nearly $100 billion to establish a limited defensive capability against intercontinental and tactical ballistic missiles with a layered mix of long-, medium- and short-range interceptors and sensors. Of most concern to the Pentagon are ballistic missiles that could be launched by North Korea or Iran.

Although MDA officials say they have the technology to “discriminate” between warheads and decoys, military experts admit that they face formidable hurdles.

The means to quickly detect an attacking warhead in a cloud of chaff have yet to be achieved, says Navy Capt. Joe Horn, former commanding officer of the USS Lake Erie, which is one of the cruisers assigned to missile defense missions.

The missile defense technology that underpins the Navy’s effort has been in development for decades, and in recent years has shown signs that it may work. Nine ships will be in place by the end of the year and the rest would arrive by 2011.

“The real problem in ballistic missile defense is not hitting a bullet with a bullet. Our interceptors can do that,” Horn says, speaking at a conference of the Surface Navy Association.

The downfall is the radar technology, which dates back to the 1960s. “Its capabilities in target discrimination we are just beginning to understand,” Horn says. The challenge is to discern “what’s in the target complex” as it flies above the atmosphere. “Somewhere in the mess is the threat we want to kill,” he says. “People criticize the X-band radar and Spy radar as being old technology and not designed to discriminate. But there is capacity to do that with new techniques.”

The ground-based missile defense system now being built in Alaska and California also is hindered by its inability to discriminate, says former U.S. ambassador Henry Cooper, who in the early 1990s was director of MDA’s predecessor, the Strategic Defense Initiative Organization.

“They are ignoring the most significant countermeasures problem,” Cooper says in an interview. “These problems have been known for years.”

The most effective tactic for beating the countermeasures is to avoid them altogether by destroying the enemy missile immediately after launch, in its so-called “boost phase,” Cooper says. Current U.S. missile defense systems would have difficulty doing that because the interceptors are not fast enough, he says. “The only way to deal with threats is to intercept them in the boost phase before they can release decoys.”

Faster “kill vehicles” had been developed under Cooper’s watch as part of a program known as “brilliant pebbles,” which later was discontinued. “If you have a lighter front end, you can achieve higher velocity,” says Cooper.

The Navy’s SM-3 interceptor missile could deploy the brilliant pebbles-era lightweight kill vehicles and drastically increase its capability to destroy a target in the boost phase, he adds.

Navy Adm. William Fallon, head of U.S. Central Command, says that once an enemy missile is allowed to reach a high altitude and leave the atmosphere, it becomes exceedingly more difficult to defeat.

“The ability to do something about this missile at the various stages of its flight [would be ideal] if we had unlimited resources and we had the technology,” he tells reporters. “This is very difficult. … From my perspective it would be useful if we had the means to do something about things early in flight.”

The current Navy Aegis ships have powerful radar systems to enable them to get “much better definition on the missile as it’s ascending,” says Fallon. But he believes the technology needs to be improved. “It is time to grow that capacity.”

Discrimination is “always going to be the most difficult thing for missile defense to do,” says Victoria Samson, a research analyst at the Center for Defense Information.

MDA consistently has failed to test the ground and the naval missile defense systems against targets that deploy countermeasures, she says. “Tests are scripted. … They need to test what they may see in the field — multiple targets that the interceptor would have to discriminate.”

The Navy has tested the Aegis missile defense system nine times and scored hits in seven of them. The high success rate is misleading, however, says Samson. “The primary cause of one flight test failure — the new guidance control system (the solid divert and attitude control system or SDACS) — still is not being used in its most advanced mode, which may affect its maneuverability against more demanding targets,” she says.

The Raytheon Company, which makes the SDACS, says it has fixed the system. “The flight test that was supposed to have gone off in December had a fully operational SDACS,” according to a Raytheon spokesman. “The missile was not launched [because of an incorrect system setting aboard the USS Lake Erie], so the same weapon will be used when we fly again in the spring.”

Critics of the current missile defense program, meanwhile, argue that it will be virtually impossible to discriminate against every form of countermeasure and that the “hit-to-kill” approach is far too risky. In a real-world missile attack, says one former MDA engineer, the U.S. defensive systems would essentially be throwing a “Hail Mary” pass with the odds greatly in favor of the enemy missile.

The whole discrimination conundrum could be avoided if the United States deployed fast interceptors that could be launched from ballistic-missile submarines at sea, he says.

Supporters of this concept have for nearly 20 years tried to convince MDA that it should develop a “trajectory optimized high altitude targeting” system using D-5 submarine launched ballistic missiles. This technology, advocates contend, eliminates the discrimination uncertainty because scores of miniature kill vehicles quickly hit the target in the boost phase.

Cooper says this concept is “technically realistic” and could be executed at a relatively low cost. The Navy’s D-5 missiles “would be more robust than what we are deploying in Alaska,” Cooper says. But the United States would stoke a global political firestorm if it deployed such a system, he asserts. “It would be hard to tell the difference between a defensive D-5 and one carrying a nuclear warhead.”

The current MDA plan puts most of the emphasis on hitting the incoming warheads in their terminal phase, as they reenter the atmosphere. “The Navy can’t do boost phase,” says Cooper. “It needs additional sensors and an interceptor that can go faster.”

The Navy SM-3 Block IA is equipped with a kinetic non-explosive warhead designed to destroy a ballistic missile’s warhead by colliding with it outside the atmosphere, during the enemy missile’s midcourse phase of flight. An improved version, the Block IB, is intended to provide some capability for intercepting intermediate-range ballistic missiles. The Block IA and IB do not fly fast enough to offer a substantial capability for intercepting ICBMs, says Ronald O’Rourke, a senior analyst at the Congressional Research Service. A faster-flying version of the SM-3, called the Block II/IIA, is now being developed to give Aegis ships a capability for intercepting certain ICBMs.

Three flight tests are planned for 2007. The Navy is hopeful that if the tests show the system is progressing, it will be able to secure funding for 18 new cruisers. An “analysis of alternatives” scheduled to be completed by May will propose a variety of hull designs, says Rear Adm. Barry J. McCullough III, director of surface warfare. The new cruiser — estimated to cost $3 billion apiece — would be equipped with a higher performance radar than current Aegis ships.

It is not clear to what extent a new cruiser would fix the current shortfalls in Navy missile defense, Samson says. From a political standpoint, the missile defense mission could make the ship easier to sell to Congress. In missile defense, she says, “ships are not what you have to worry about. It’s about the interceptor missiles that work … that are reliable and can be mass-produced. … Ships are not what they are lacking.”

L. Paul James III, a retired Navy officer who worked on missile defense projects, argues that the Navy is in danger of losing funding and political support for missile defense unless it “embraces the mission” and commits substantial resources. Any terminal or mid-course systems deployed by the Navy would be severely limited if the service did not procure enough interceptors, James writes in the U.S. Naval Institute Proceedings. The costs will be significant, he notes. “Even if the Missile Defense Agency pays for system upgrades and some of the missiles, the Navy will have to supply the bulk of the interceptor inventory, the people, the training, the ships and the supporting infrastructure.”

As it charts the way ahead, the Navy must take into account that the ground-based missile defense system being built in Alaska could drain funding from the sea-based system, O’Rourke says.

“A sea-based system might be more expensive to procure than an equivalent ground-based system due to the potential need to engineer the sea-based system to resist the corrosive marine environment, resist electromagnetic interference from other powerful shipboard systems and meet shipboard safety requirements, or fit into a limited space aboard ship,” he notes. “A BMD system on a ship or floating platform that is dedicated to BMD operations might be more expensive to operate and support than an equivalent ground-based system due to the maintenance costs and the need for a crew of some size to operate the ship.”

Another concern is the vulnerability of Navy ships as they deploy near hostile waters, says O’Rourke. “A sea-based BMD system operating in a forward location might be more vulnerable to enemy attack than a ground-based system, particularly a ground-based system in a less-forward location. Defending a sea-based system against potential attack could require the presence of additional Navy ships or other forces.”

A major assist to the Navy’s program is Japan’s investment of $1.5 billion in Aegis missile defense technology. “U.S.-Japan cooperation will expand even more because the Japanese have had significant emotional events,” says Air Force Lt. Gen. Henry A. Obering, III, director of the Missile Defense Agency. Japan sees North Korea as an “urgent” threat, he says during a speech to the Surface Navy Association.

The U.S. ground-based system so far has 12 interceptors in place, and there will be 14 in Alaska and two in California by the end of the month, says Obering. He anticipates a total of 24 by the end of 2007. The Navy has 14 SM-3 interceptors in operation, and is expected to build 21 by the end of the year, with a goal of reaching 83 in the next five years.

The sensors in the ground system are not yet up to par, says Obering. A new radar soon will be installed in the United Kingdom. “That will give us the first capability to defend ourselves against the Middle Eastern threat,” he says. “Interceptors in Alaska and California have the reach to protect us from a ballistic missile threat, but we don’t have the sensors today, but we are rapidly closing that out.” A sea-based X-band radar is on its way to Alaska. “It’s powerful enough that if we placed it in the Chesapeake, we could discriminate and track a baseball-size target over San Francisco.”

The goal is to build 44 interceptors in the United States — 40 in Alaska and four in California. Two others will be based at a European site, to help expand coverage. A large X-band radar will be moved from the South Pacific to Europe to provide more coverage.

Additional reporting by Grace V. Jean

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