WASHINGTON — The U.S. Defense Department’s forthcoming 2010 budget request for missile defense programs emphasizes protecting U.S. troops and allies from short- to medium-range threats using deployment-ready systems.

During a press briefing April 6, Defense Secretary Robert Gates said spending on Missile Defense Agency (MDA) programs will decline by $1.4 billion in 2010. While funding details for most programs have yet to be released, Gates announced some key decisions, among them the cancellation of plans to build a second Airborne Laser platform.

The Airborne Laser, a converted Boeing 747 aircraft equipped with a high-power laser for downing missiles in their boost phase, has progressed through a series of tests leading up to a planned first attempt to engage a missile in flight this year. Chicago-based Boeing Co. is the prime contractor.

“The [Airborne Laser] program has significant affordability and technology problems, and the program’s proposed role is highly questionable,” Gates said.

The forthcoming budget request also terminates the Multiple Kill Vehicle, a system designed to deal with the problem of distinguishing between active missile warheads and decoys by destroying all possible targets in the immediate vicinity. Lockheed Martin Corp. of Bethesda, Md., was prime contractor on that effort, and Raytheon Co. of Waltham, Mass., was developing a competing design. The program faced significant technical challenges and the requirement for such a system must be revisited, Gates said.

For the Ground-based Midcourse Defense system, the primary U.S. territorial shield, funding will continue to support operations and technology development, but no new interceptors will be purchased, Gates said. The MDA has either taken delivery of or issued a contract for each of the 44 interceptors planned for sites at Fort Greely, Alaska, and Vandenberg Air Force Base, Calif.

A decision on whether to fund the proposed European missile defense site is still awaiting a decision from its two host nations, Poland and the Czech Republic, and the results of the Pentagon’s upcoming Quadrennial Defense Review, Marine Corps Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff, said during the same briefing. Sufficient funding remains in 2009 to continue on with work on that program, Cartwright said.

Two relatively mature programs, the Terminal High Altitude Area Defense and Aegis Ballistic Missile Defense systems, are slated for funding increases in 2010 that will enable full-scale production of their respective interceptors. By the end of this year, the Pentagon will have purchased 100 Lockheed Martin-built interceptors for the Terminal High Altitude Area Defense system and 133 Raytheon-built Standard Missile-3 interceptors for the Aegis system. The MDA will spend $700 million more next year on those interceptors than it anticipated spending in the last budget request. An additional $200 million will be spent to outfit six more Navy ships with the Aegis Ballistic Missile Defense capability.

Future missile defense research efforts will focus on knocking down ballistic missiles during the boost phase, before they can deploy countermeasures, Cartwright indicated. But the Pentagon’s approach is unclear: The Airborne Laser had been envisioned as a primary boost-phase interceptor, and Cartwright would not say what the future holds for the MDA’s other potential boost-phase system, the Kinetic Energy Interceptor being developed by Los Angeles-based Northrop Grumman Corp.

“Looking at boost phase is going to be an area that we’re going to do more [research and development],” Cartwright said. “But we’ve got to figure out what the right way forward is, what the right balance is between the midcourse and the terminal.”

Baker Spring, an analyst at the Heritage Foundation, a think tank here, expressed puzzlement at some of the missile defense decisions, saying they appear out of alignment with the Pentagon’s expressed intentions.

“There are a bunch of contradictions here,” Spring said. “Gates is fond of saying he wants to win the wars we are in today and avoid ‘next war-itis.’ But the wars we are in are marked by a fractured threat environment that calls for a strategic posture more defensive in nature than the retaliation-based policies of the Cold War. Cutting $1.4 billion from the missile defense budget; that by itself in my opinion is a mismatch.”

Spring also said the decision not to build a second Airborne Laser appears at odds with Cartwright’s suggestion that boost-phase defense will be a focus of future research.

“The one glimmer of hope here is the increased funding for the Navy’s Aegis system,” Spring said.