WASHINGTON —The administration of U.S. President Barack Obama is seeking $8.4 billion for missile defense next year, a $500 million increase over 2010, in a proposal that reflects a new strategy for defending Europe, plans to develop airborne warning sensors and greater emphasis on testing.

The 2011 budget request for the U.S. Missile Defense Agency (MDA) was influenced by the congressionally mandated Ballistic Missile Defense Review, a new strategic framework that calls for the United States to continue fielding a limited defense of its own territory while also protecting deployed forces and allies. Released Feb. 1 along with the budget request, the framework stresses budgetary sustainability, operationally realistic testing prior to deployment of missile defense systems and a focus on international partnerships.

Among the major initiatives in the request is an effort to develop a land-based variant of the Standard Missile-3 (SM-3) interceptor, which today is launched from ships at sea as part of the Aegis Ballistic Missile Defense system. The initiative is driven by the administration’s shift in strategy for the defense of Europe, announced in September.

Previously, the MDA was preparing to install interceptors in Poland and a radar site in the Czech Republic to defend Europe and deployed U.S. forces from short- and medium-range ballistic missiles. The plan, which would have utilized interceptors based on those now being installed in Alaska and California to defend U.S. territory, was staunchly opposed by Russia.

The new strategy revolves around the Aegis system, which has compiled a good track record in intercept tests. Plans call for deploying Aegis-equipped ships in European territorial waters in 2011, and deploying land-based SM-3 variants on European soil some time after that.

To that end, the MDA is asking Congress to reprogram $68.5 million of its 2010 appropriation to begin construction of an Aegis Ashore Test Facility at the Pacific Missile Range Facility in Hawaii, budget documents show. For 2011, the agency will request $281 million for land-based SM-3 development.

The agency also requests $319 million to continue development of a larger, more capable variant of the SM-3 interceptor in cooperation with Japan.

The new European approach will also rely on a new set of aerial sensors. The MDA intends to start a program next year to develop airborne infrared sensors, with the goal of fielding 12 unmanned missile warning aircraft by 2015, budget documents show. Since the summer, the agency has been using unmanned Navy Reaper aircraft to observe ballistic missile defense tests, and so far the results have been encouraging, MDA Executive Director David Altwegg said during a Feb. 1 media briefing at the Pentagon.

Also in the sensor arena, the MDA requested $67 million to begin work on a constellation of operational missile tracking satellites called the Precision Tracking Space System. The agency would conduct trade studies and software testing and complete a preliminary design review with the goal of demonstrating the system in 2014, budget documents show.

That work would draw on experiments conducted with the MDA’s three Space Tracking and Surveillance System demonstration satellites — two unclassified and one classified — that were launched last year. The MDA is requesting $84 million next year to continue testing and operation of the demonstration satellites, whose test program is being revamped amid shifting budget priorities.

Another change reflected in the budget request is the MDA’s approach to its test and target programs. The agency developed a new test program last year that will rely more heavily on modeling and simulation, for example. In addition, the MDA is upgrading its stock of target vehicles following a series of test problems involving targets based on aging U.S. missiles. The agency is holding a competition to field new medium-range targets and intends to solicit bids for new intermediate- and long-range targets this year, Altwegg said.

The 2011 budget request does not include funding for the MDA’s experimental Airborne Laser, a modified 747 aircraft equipped with a high-power chemical laser intended to shoot down missiles as they lift off. The futuristic system is poised to make its first attempt to shoot down a ballistic missile target this year, after which the platform will be turned into a ground based test bed for directed-energy weapons, Altwegg said. The budget request includes $99 million for that effort, he said.