Subs: Best Basing Mode for Boost-Phase Defense?

By RICK BARNARD
Editor in Chief

Sometime this winter, the Pentagon will take another step in its 22-year search for an effective and politically feasible missile-defense system, as it decides upon appropriate basing platforms, or modes, for U.S. interceptor missiles intended to destroy attacking ballistic missiles during their first few seconds of flight.

A decision is not expected for months, but some missile defense experts believe that the Pentagon's long and tortuous path toward development of a missile-defense system should end under water. The best basing mode available "is a submarine," an industry official told Sea Power. "You buy yourself lots of flexibility with subs as a basing mode. You can move a lot closer to the [adversary's launch sites]. And the closer you get, the easier it becomes to [intercept the attacking missile] in the boost phase. That is a huge advantage." Boost phase, the attacking missile's initial trajectory from launch to altitudes of about 300 miles within the first 150 to 300 seconds of flight, is the best--but most difficult--phase to destroy attacking missiles. The Pentagon's Missile Defense Agency (MDA) calls it "the ideal solution."

Terry Little, program director of MDA's Kinetic Energy Interceptor office, is considering the costs and benefits of launching kinetic-energy interceptor missiles from Aegis-equipped warships, submarines, or cargo ships.

Little, in mid-September, was preparing his recommendations to Air Force Lt. Gen. Ronald Kadish, MDA director, and hoped for a final decision by year-end. For several experts in the missile-defense field, however, the decision is a no-brainer. They are convinced that linking the missile-defense program with the nation's original stealth weapon creates great advantages for the United States. A retired admiral with decades of experience in the submarine field, said, "with subs, you have the advantage of ambiguous presence" because the enemy always is uncertain about their location. Other advantages are submarines' endurance and stealth qualities, and there is no need for a defensive force to protect submarines.

Initial sea-based portions of the Pentagon's multilayered missile defense system would be based on the Aegis Weapon System and deployed by 2006. A more advanced kinetic-energy interceptor missile would be fielded as a ground-based element of a missile defense system by 2010. A sea-based version would follow by 2013. A kinetic-energy missile has no warhead and instead relies on the force of its impact at intercept to destroy the attacking missile.

It is the possible combination of the kinetic-energy missile and the submarine that excites enthusiasts of sub-based missile defenses. The marriage of the two weapons would make it easier to intercept attacking missiles in the boost phase, which would enable the United States to take the fight to the enemy, rather than engage closer to the U.S. homeland.

"Also, the debris problem is resolved," said an industry official. "It falls back on the attacker, rather than on us." Another advantage is that in boost phase, the attacking missile has not yet initiated its countermeasures, which can include decoys designed to look like missile re-entry vehicles, chaff, and the use of multiple warheads or sub-munitions on each attacking missile.

A July 2003 report by the American Physical Society on "Boost-Phase Intercept Systems for National Missile Defense" asserts that an adversary could make the task even more difficult by switching to solid fuel rockets, which have shorter burn times relative to liquid-propellants, making them more difficult to intercept. "Boost-phase defense of the entire United States against solid-propellant intercontinental ballistic missiles . . . is unlikely to be practical when all factors are considered, no matter where or how interceptors are based," the society report concluded.

Tremendous acceleration, speed, and power are required to intercept an attacking missile in the few seconds available during boost phase. It requires a new, fast missile that does not yet exist. Little was assigned to the MDA in October to develop such an interceptor. A seasoned Air Force official best known for his successful management of the Joint Direct-Attack Munition used in great numbers in Afghanistan and Iraq, Little envisions a kinetic-energy missile that would speed toward the target at 6 kilometers per second. Burn time for the two-stage, 7,500 kilogram missile would be 60 seconds, according to Little's briefing paper, which contained generic characteristics for a missile designed for intercepts in the boost, assent, and midcourse phases of an attacking missile's trajectory. The assent phase occurs about 500 to 600 seconds into the flight, after initial countermeasures are deployed. Midcourse is at the apex of the missile's flight at about 1,200 seconds of flight time.

Little has pitted two teams of defense contractors in a race for MDA's development and production contracts to deploy a kinetic energy weapon: Lockheed Martin is paired with Boeing against Raytheon and Northrop Grumman.

Advocates of sub-based missile defenses believe that the stealth characteristics of submarines would provide huge advantages to a multilayered missile-defense system. The stealth qualities of the submarine place an adversary in tactical limbo because "the enemy is never sure whether it is there or not there," said a retired admiral. "And it would not need to be protected. If a surface ship is your launch platform, you'll have to send other ships out to protect it."

Communications long were considered the Achilles heel of submarines during some missions, because lack of bandwidth placed restraints on some operations. Communications are vital during missile-defense missions. In recent years, however, both attack and ballistic-missile submarines have been equipped with a variety of antennas to bolster communications flexibility. For example, high data-rate antennas have vastly improved communications with commercial and defense satellites, such as the Defense Satellite Communications System. "Communications during missile-defense missions would not be a problem ...," an industry executive told Sea Power.

Trident ballistic-missile submarines are an obvious choice as a basing mode in a multilayered missile defense system, experts say. The 14 remaining Trident boats have many years of life left in them. Their missile tubes, 84 inches in width, could accommodate almost any missile, thanks in part to the development of encapsulation methods that enable subs to launch a wide variety of weapons, from Army missiles to Unmanned Underwater Vehicles. The innovative submarine payload integration approaches began in 1999 in the joint DARPA/Navy Submarine Payload and Sensors program. Today, Raytheon and General Dynamics are working on the Broaching Universal Buoyant Launcher, for example, while Northrop is developing the Stealthy Affordable Capsule and General Dynamics is designing the Flexible Payload Module.

Interceptor missiles also could be launched from the new Virginia-class attack boats with a modular hull insert or the four Trident boats now being converted to guided-missile submarine (SSGN) configuration to fire Tomahawk missiles and transport special operations forces. But the Tridents might be the best choice, said one expert. "We have 14 boats, each with 24 tubes and five warheads [multiple independently targetable reentry vehicles] on each missile in the tubes. That gives us 1,680 warheads. How many do we need nowadays?"