The United States is facing a vast array of new threats, but the country's troop deployments (search) have yet to catch up, say defense policy experts.

For instance, Germany once housed a quarter of a million American servicemen. That number is now 73,000, but much of their reason for being there — facing off America's Cold War enemy — is gone.

"A lot of where we have forces around the world, our relationships that sort of froze in place a long time ago, had a logic that was based on an earlier time technologically and an earlier time historically," said a senior State Department (search) official at a defense policy briefing earlier this month.

The Defense Department is now in the midst of a Global Posture Review (search), part of Secretary of Defense Donald Rumsfeld's plan to reform and update the military. Senior Pentagon officials say the emphasis in the new GPR will be on maintaining force capability, but doing so with more agility and better technology.

The final report may not be out for a year or more, but speculation surrounding the worldwide basing changes include reductions in South Korea and Western Europe, new bases in Eastern Europe, maintaining capacity in Central Asia and boosting abilities in Guam. The Pentagon will make some of these changes, such as the withdrawal of thousands of troops from South Korea,  in advance of the report's release.

But even with new changes and challenges, a senior Defense Department (search) official warned against reaching early conclusions.

It would be a mistaken strategy "to say that we know precisely where we're going to fight and therefore we can position an asset or capability ... we're more likely to be working with our partners to develop capabilities so that we can move to where the challenges will likely be," the official, who asked not to be identified, said at the Pentagon briefing on June 9.

Administration officials were careful to stress that new basing decisions will be determined according to capabilities.

"The focus here has been on capabilities and not numbers; that is, we need to ensure that we and our allies have the right capabilities to deal with the security challenges that we face. We'll then make a determination of whatever the numbers are. But if we begin this with numbers, we're almost sure to get it wrong," said the senior DOD official.

America has its largest foreign bases in Germany, Japan and South Korea, and America's commitments in these countries will likely be key elements in the GPR.

Last month, the United States informed South Korea and Japan that 3,600 American troops would be shifted from South Korea to Iraq. Earlier this month, the Pentagon announced that by 2006 America will withdraw some 12,500 troops from South Korea, reducing the force to approximately 25,000.

Despite this withdrawal, American officials have assured the South Koreans that other upgrades, such as more air power and unmanned aerial vehicles, would make up for the smaller number of troops. Those upgrades are expected to cost $11 billion over five years.

Finances are also a factor in deciding the force posture. Maintaining a large garrison in a wealthy country like Germany is expensive, and Germany's stiff environmental regulations make training exercises a headache.

As a result, Washington will likely move forces to allies further east, where basing is cheaper and exercises are easier. The Pentagon has not announced any moves, but speculation has focused on Poland, which has a significant contingent in Iraq, and Bulgaria, which is close to the Middle East. The Baltic countries and Hungary are also in the mix.

"There is some possibility of troop shifts out of Germany into Eastern Europe — Romania, Bulgaria and Hungary," said Peter Brookes a senior fellow at the Heritage Foundation. "We want to place our forces closer to where they may be needed."

Although Eastern Europe is closer to future hot spots, it may not be close enough.

"The chances of a major conflict in Europe are about zero," Brookes said. Bolstering newly established bases in Central Asia and the Middle East might make more sense, he said.

But, Victoria Samson, research analyst at the Center for Defense Information (search), said military and political reasons dictate maintaining a presence in Europe.

"It may be something along the lines of welcoming our new NATO (search) partners or reminding the Russians" that America still has commitments to Europe, she told Foxnews.com.

The United States still maintains significant European bases in Great Britain and Italy. Italy points to the Middle East and is considered a logical jumping off point from Europe. Britain, on the other hand, is much further away. The base in Britain primarily houses the Air Force, and for these forces to get to the Middle East, the United States would have to negotiate flying over such countries as France and Germany. Still a pullout from Britain may not be imminent.

"I think it would be a pretty heavy political blow to the British government. Since we made such a big deal about them being our special partners, it would be disheartening," Samson said.

Japan is another major strategic concern for the United States. America has more than 40,000 servicemen based in the country, but because Japan is a close ally and is near both China and North Korea, shrinking the forces there is unlikely. Because of potential threats from the Far East, America is also likely to bolster its presence on the Pacific island of Guam, which has the added advantage of fewer political complications because it is an American territory.

Brookes, who is a former deputy assistant secretary of defense for Asian and Pacific affairs, explained that America cannot conduct Pacific security solely from Hawaii and California because of the "tyranny of distance." The Pacific is a vast ocean, and being able to move men and material rapidly is one of the keys to winning wars.

"Amateurs study strategy, and professionals study logistics," said Brookes. It is "really critical that you are able to move those forces in the right amount and the right mass."

Any troop shifts will not be done unilaterally, but will be done in careful consultation with allies, administration officials said.

The report is unlikely to be completed by May, when the secretary of defense will submit recommendations to the Base Closure and Realignment Commission (search).

"We definitely do not need to come to completion of this prior to closure of BRAC," a senior administration official said.

The Pentagon has been working on the study phase of the GPR for 18 months, and it has no deadline for completion. Pentagon officials have refused to speculate when lawmakers might be briefed and what the GPR will contain.