In 1940, Winston Churchill declared Singapore safe. It was "not considered possible that the Japanese ... would embark on such a mad enterprise." When the Japanese arrived in February 1942, Singapore fell in a week.

"The man in the street had been led to believe that Singapore was an impregnable fortress upon which the safety of Australia, New Zealand and India depended," wrote British historian Major-General S. Woodburn Kirby. "This belief had been rudely shattered."

The loss of Singapore was devastating for the Brits. It was their only major naval base in South Asia. Japan intended its attacks on Pearl Harbor and U.S. bases at Subic Bay to drive America out of Asia, much in the manner it had rolled back British power by taking Singapore.

The imperial navy understood what many in Congress can't seem to get: Global bases are an essential part of being a global power. Last May, Sen. Jon Tester, D-Mont., wrote then-Defense Secretary Robert Gates:

"Given the U.S. military's advanced technology and the capability of our forces to deploy throughout the world from stateside bases, I believe there may be added value in further reducing our foreign basing footprint."

Since then, many have echoed Tester's view. But U.S. overseas bases are not "piggy banks" to be cashed out to help balance the budget.

For starters, it is fiscally naive to propose defense cuts as budget balancing tool. Washington could take defense spending to "zero" today, but absent significant reforms to Social Security, Medicare and Medicaid, the government would still be bankrupt in 40 years.

More importantly, trying to balance the budget in ways that compromise national security makes no sense. Defense investments ought to rise and fall on their own merits. And few U.S. investments give a better return on the dollar than overseas bases.

The notion that U.S. overseas bases are a Cold War leftover is largely myth. Case in point: Europe. At the end of the Cold War, the U.S. closed many of it European bases, and more are slotted to go. In the next five years, the Army will turn more than 22 installations to the Germans.

But while we've been closing some bases, we've also been opening or expanding others -- adapting the overseas footprint to enable the military to defend U.S. interests. Bases in Europe, for example, now primarily serve as staging areas to project American forces elsewhere.

When it comes to dealing with two-thirds of our national security problems -- everything from battling the Taliban to keeping watch on Iran -- the U.S. ships, planes and soldiers based in Europe are "halfway there."

In many cases, "host" countries pick up a significant part of basing costs. South Korea, for example, pays almost half the cost of basing U.S. troops in that country.

Bases enable to U.S. to get somewhere and stay there at a reasonable cost. U.S. fighter aircraft, for example, need repair parts every few days. Having parts and maintenance facilities on hand is dramatically cheaper than running back to the U.S. every time a plane needs to be fixed, rearmed or refueled.

Geography matters. If the U.S. did not have global bases, it would need twice as many ships, planes and troops to cover the same missions. We'd have to build additional bases here to house all those resources, and we'd still need to send them halfway around the world to get to the problems they're asked to solve. That is simply unaffordable. Cutting bases is anything but an exercise in military efficiency.

Without global bases, the U.S. will no longer be a global power. It is just that simple.

James Jay Carafano is a senior research fellow for national security at the Heritage Foundation.