The United States could use a modified existing Raytheon Co. [RTN] air-to-air missile to shoot down enemy ballistic missiles in their vulnerable boost phase, according to Loren Thompson, chief operating office of the Lexington Institute, a think tank near the Pentagon focusing on defense and other issues.

This Network Centric Airborne Defense Element, or NCADE, would provide bargain basement protection from enemy missiles, costing less than $1 million per enemy weapon killed, Thompson argued in a recent paper.

Raytheon also works with Northrop Grumman Corp. [NOC] on a much more advanced, high-tech system to take out enemy missiles shortly after launch, in their boost phase, called the Kinetic Energy Interceptor. It is an interceptor missile that would hit and kill enemy weapons.

As well, The Boeing Co. [BA] is the prime contractor on the Airborne Laser program, that also kills enemy missiles in their boost phase, contributing as well the heavily modified 747-400 aircraft on which the laser is mounted. Northrop provides the laser, and Lockheed Martin Corp. [LMT] contributes the beam control/fire control system.

While a fleet of eight or so aircraft might have substantial cost, the cost thereafter of shooting down an enemy missile with a beam of light would be small.

Thompson noted that the Department of Defense is under pressure to cut spending.

"But the core missions of the military won’t go away, so the search is on for more cost-effective solutions to security challenges," Thompson wrote.

He argues that NCADE would be a cheaper means of annihilating enemy missiles than most other ballistic missile defense (BMD) systems in the overall layered U.S. anti-missile shield.

"Raytheon has come up with a low-cost approach to missile defense — arguably the single most important mission the military has — that is so elegant and compelling that it could serve as a model for other cost-saving breakthroughs," Thompson argued.

"What the Massachusetts-based company has done is adapt an air-to-air missile already in widespread use so that it can intercept ballistic missiles in the most vulnerable phase of their trajectory, before they have released multiple warheads or countermeasures to assist in penetrating defenses."

He noted that it is easier for a U.S. BMD shield system to spot an enemy missile just after it is launched.

"At that stage in its flight, a ballistic missile is relatively fragile and easy to spot because of the huge exhaust plume it generates," Thompson wrote. "Missile defense experts have long known that boost/ascent was the optimum time to attempt intercept of a hostile missile, since a single strike can destroy all of its warheads while minimizing the challenge presented to defenders later in the trajectory."

In the midcourse of an enemy weapon in its ballistic flight, or in its terminal phase as it descends upon its American or allied target, there is no exhaust plume, and multiple warheads, confusing chaff or decoys may be deployed.

"In the later stages, when the payload is coasting through space or undergoing re-entry, warheads are harder to sort out from surrounding debris and track, especially if the attacker is smart enough to disguise them," Thompson argued.

Despite all these facts, there is a reason that few U.S. missile defense systems attempt to kill enemy missiles in their boost phase, he continued.

"The reason missile defense planners typically focus on intercepting attackers in those later phases is because of the difficulty of getting close enough to a launching missile to hit it during the few minutes before it reaches space and releases its warheads.

"But by adapting an air-launched missile already in use on supersonic fighters for the boost/ascent phase intercept mission, Raytheon has crafted an affordable, low-risk complement to the bigger and more costly systems that are required to intercept fast-moving ballistic bodies in the later stages of their trajectory."

That NCADE system by Raytheon "would be carried close to the enemy launch site on its host aircraft, and then released at high altitude to attack the rising missile," Thompson noted.

"By netting together sensor inputs from a variety of existing systems such as Aegis destroyers and JSTARS radar planes, the aircraft could be vectored to the best release point for its interceptor. The interceptor would then use a heat-seeking sensor in its nose adapted from another existing air-to-air missile to achieve impact kill of its target."

A variety of platforms could launch NCADE, Thompson continued.

"NCADE could also be launched from a loitering unmanned aircraft such as the Air Force’s Reaper. In fact, it could be launched from a wide range of aircraft, because it has the same external configuration as the air-to-air missile on which it is based, despite the introduction of a new seeker and second propulsion stage. That means no expensive aircraft modifications or new infrastructure would be required. The interceptor would cost less than a million dollars per copy to produce, and could be ready for use in a few years."

To be sure, Thompson isn’t claiming that NCADE would be a magic bullet hitting a bullet, the enemy missile, or a one-size-fits-all answer to every U.S. missile defense need.

Still, "it is the least expensive, highest leverage solution to a major threat that anyone has proposed in a long time," Thompson concluded.