WASHINGTON — The Pentagon has drafted plans to withdraw as many as half of the 71,000 troops based in Germany as part of an extensive realignment of American military forces that moves away from large concentrations in Europe and Asia, according to U.S. officials.

Under the plan, which is nearing approval, smaller, relatively spartan bases would be established in Romania and possibly Bulgaria and would be designed for the rapid projection of U.S. military power against terrorists, hostile states and other potential adversaries. Training facilities would be set up in Poland.

Farther east, in central Asia, bases in Uzbekistan, Tajikistan and Kyrgyzstan that were established in 2001 to support the war in Afghanistan would be preserved as unmanned staging areas that U.S. forces could use in emergencies.

In Asia, about 15,000 troops out of a total presence of about 100,000 would be withdrawn, mostly by streamlining administrative staffs of the U.S. military commands in South Korea and Japan, the officials said. But much of that reduction could be offset by a buildup of personnel and aircraft in Guam and the possible stationing of another aircraft carrier battle group in either Guam or Hawaii, the officials said. The Pentagon plan also calls for new training and staging areas in Australia and expansion of military ties with Singapore and Thailand.

U.S. officials have said before that they intended to eliminate a number of large, full-service Cold War bases abroad and construct a network of more skeletal outposts closer to potential trouble spots in the Middle East and along the Pacific Rim. But neither the proposed size of the reductions in Europe and Asia nor details about locations of the new sites have been previously disclosed.

The realignment would amount to a dramatic change in how U.S. forces are positioned around the globe. Some of the troops now overseas would be brought home, while vital equipment would be dispersed more widely to enable more nimble dispatch of forces. Another major objective, officials added, is to deepen military ties and joint training with a greater number of allies in Eastern Europe, Central Asia, Africa and Southeast Asia.

Several senior administration officials involved in the planning said President Bush and his national security advisers are still a month or two away from approving the changes. Some key details have yet to be resolved, officials said, and more consultations with allies will be held.

The planning reflects a recognition that potential threats have changed since the Cold War ended, said Douglas Feith, Pentagon undersecretary for policy and an architect of the global realignment plan.

"One of the main arguments for forward deployment in the old days was, you had a sense that you knew where you were going to fight and so you positioned your forces where you thought you were going to fight," Feith said. "Our view now is you have to move to the fight."

In western Europe, which hosts about 102,000 U.S. military service personnel, most of the expected reduction would come in Army forces in Germany. The Army would withdraw more than 60 percent of its 56,000 troops in Germany, home to the 1st Armored and 1st Infantry divisions, officials said, and several overlapping high-level commands would be consolidated.

The nature of the remaining force would change as well. Armored units there now would leave and be replaced in part by lighter, easier-to-deploy forces, possibly including a brigade of Stryker infantry combat vehicles — lightly armored wheeled vehicles central to the Army’s shift toward more agile, mobile units. Additionally, some troops sent to Europe would go for short rotations without families, instead of more traditional three-year tours with families.

Some substantial U.S. military operations would remain in Germany, including Ramstein Air Base, which defense officials view as a critical hub facility for supporting deployments to more distant places. But some U.S. fighter aircraft may be shifted to the Middle East.

"The one thing I would stress, because it comes up all the time, is the notion that we’re withdrawing forces to punish the Germans somehow" for their lack of support for the U.S.-led invasion of Iraq, Feith said. "What we’re doing is not at all tied to current events. We’re looking at this in terms of changes that will last decades."