It was not Prime Minister Gordon Brown's finest hour. In his D-Day speech earlier this week, the beleaguered British leader solemnly announced:

"Next to Obama Beach, we join President Obama in paying particular tribute to the spectacular bravery of American soldiers who gave their lives."

Most assume it was a Freudian slip or a teleprompter malfunction (something from which Mr. Obama himself has been known to suffer). But maybe there's more to think about here.

Europe today is much different from the continent where Allied forces landed 65 years ago. On that first D-Day, it was all about "hard power." From ships to landing craft, jeeps to tanks, men to material, everything and everyone involved in the landings were focused on using military might to crack open Hitler's "Fortress Europe."

But today, while many German pillboxes remain in Normandy (and look as if they'd be difficult to overtake, even with modern weapons), the rest of Europe has changed. Its focus now is on "soft power," chiefly diplomacy and aid.

Many, if not most, Europeans credit "soft power" for the peace they've enjoyed for decades. Thinking their version of a Kantian universal peace arose from the committee chambers of the European Union - and not from the victories of the Western powers in World War II and the Cold War - they hold up soft power as a model for the rest of the world.

In their view, bridging the often hardened differences between states and shaping their decisions requires mainly negotiation and common understanding. The importance of our military strength is downplayed and sometimes even seen as the main obstacle to peace. Even when its importance is acknowledged, it's a perfunctory afterthought.

Many liberals are now pressing the U.S. government to adopt this vision, too. But the futility of it can be seen everywhere, from the failure of negotiations to deter both Iran and North Korea from their nuclear programs over the past five years - a period in which their efforts have only matured - to the lackluster response to Russia's invasion of Georgian territory.

The limits of soft power have not only bedeviled Mr. Obama but George W. Bush as well. After applying pressure on North Korea so diligently in 2006, the Bush administration relaxed its posture in early 2007, and North Korea concluded that it was again free to backslide on its commitments. Two years later, this effort to "engage" North Korea, which the Obama administration continued even after North Korea's April 5 missile test, has only led North Korea to believe that it can get away with more missile tests and nuclear weapons detonations. And so far, it has.

The problem here is not merely an overconfidence in the process of "talking" and trying to achieve "mutual understanding" - as if diplomacy were merely about communications and eliminating hurt feelings. Rather, it is about the interaction and sometimes clash of hardened interests and ideologies. These are serious matters, and you don't take them seriously by wishing away the necessity, when need be, of using the hard power of force to settle things.

It's this connection of hard to soft power that Mr. Obama appears not to understand. In what is becoming a signature trait of saying one thing and doing another, Mr. Obama has argued that America must "combine military power with strengthened diplomacy." But since becoming president he has done little to demonstrate an actual commitment to forging a policy that combines America's military power with diplomatic strategies.

For America to be an effective leader and arbiter of the international order, it must be willing to maintain a world-class military. That requires resources: spending, on average, no less than 4 percent of the nation's gross domestic product on defense. Unfortunately, Mr. Obama's next proposed defense budget and Secretary of Defense Robert M. Gates' vision for "rebalancing" the military are drastically disconnected from the broad range of strategic priorities that a superpower like the United States must influence and achieve.

If our country allows its hard power to wane, our leaders will lose crucial diplomatic clout. This is already on display in the western Pacific Ocean, where America's ability to hedge against the growing ambitions of a rising China is being called into question by some of our key Asian allies. Recently, Australia released a defense white paper concerned primarily with the potential decline of U.S. military primacy and its implications for Australian security and stability in the Asia-Pacific. These developments are anything but reassuring.

The ability of the United States to reassure friends, deter competitors, coerce belligerent states and defeat enemies does not rest on the strength of our political leaders' commitment to diplomacy; it rests on the foundation of a powerful military. The United States can succeed in advancing its priorities by diplomatic means only so long as it retains a "big stick." Only by building a full-spectrum military force can America reassure its many friends and allies and count on their future support.

The next British leader - and the rest of our allies - need to know they can count on the U.S. to intervene on their behalf any time, anywhere it has to. That will require hard power, not just soft, diplomatic words murmured whilst strolling serenely along "Obama Beach."

Kim Holmes, a former assistant secretary of state, is a vice president at the Heritage Foundation and author of "Liberty's Best Hope: American Leadership for the 21st Century" (2008).