Being a superpower is not like being a duke or an earl. It’s not a hereditary title, not a status you retain however modest your circumstances become. Being a superpower is more like being the heavyweight champion. You keep the designation so long as you’re willing to fight for it – and so long as you best every opponent who takes you on.

The United Kingdom once was a superpower. There was a time when it could do what a superpower does: project force and shape events around the globe. After World War II, it lost that ability.

For generations, the Soviet Union was considered a superpower. In the 1980s, however, it became apparent that the communist regime was in steep decline both economically and militarily. Its defeat by Islamist guerrillas in neighboring Afghanistan was followed by the tearing down of the Berlin Wall. That marked the end of an empire and an era.

Today, it is said, the U.S. is the last remaining superpower. But is it? Its enemies think not. America’s defeat in Vietnam, its hasty withdrawal from Beirut after the Hezbollah suicide-bombings in 1983, its retreat under fire from Mogadishu ten years later – these and other events gave rise to the theory that American strength is an illusion: The U.S. may look tall and strong, but hit it and it will collapse – much like the World Trade Center. That’s what Militant Islamists seek to do.

Ironically, it was immediately following the attacks of 9/11/01 that America seemed most entitled to be called a superpower. U.S. forces quickly toppled the Taliban in Afghanistan. Then, in Iraq, the United States caused Saddam Hussein to flee his palaces and take refuge in a spider hole.

But in the many months since, America’s ability to work its will has been sorely tested. The terrorists and insurgents in Iraq have never won a battle against U.S. forces. But – as U.S. political and military leaders have been slow to understand – they haven’t needed to.

To be perceived as the victor these days, they merely need to keep blood dripping in front of camera lenses day after day. That’s easy to do: In Iraq, as in so much of the region, there is no shortage of cash (thanks to the Western appetite for oil), explosives (due to decades of militarization) and individuals seeking the eternal rewards of martyrdom (having been indoctrinated by radical clerics).

It doesn’t even matter whether the bodies that pile up are those of “infidel” soldiers or Muslim civilians. Either way, the carnage is counted as a loss for the U.S. and a win for the “resistance.” That is a distorted perspective, militarily and morally, but it is the dominant perspective within the media and among intellectual elites.

Meanwhile, the Islamist regime in Iran is using terrorist groups – Hezbollah in particular -- to project its power globally, while simultaneously pursuing nuclear weapons and the means to deliver them. The goal is clear: to become a superpower for the 21st century – loosely modeled on the superpower that emerged in the 7th century and which dominated the world for a nearly a thousand years thereafter.

Allowing this to happen would represent a mistake of historic proportions, akin to enabling the rise of Hitler in the 1930s. Yet, now as then, only a small percentage of Europeans are prepared to do what is necessary to resist tyranny.

That leaves the problem for America to solve. But it will not be easy for the U.S. to act as the lone superpower at a time when there is increasing doubt about whether America still is a superpower, doubt about whether America has either the will or a way win post-modern wars and shape the future.

If the U.S. decides to rise to the challenge, it may not succeed. If it backs away from the fight, failure is guaranteed. And should a fanatical, oil-rich, nuclear-armed, terrorist-sponsoring superpower arise in the Middle East, the consequences will be dire.

To prevail in the current global conflict will be no cakewalk. It will require enormous determination, courage, energy and creativity. There will be casualties. There will be setbacks. Americans will not be loved. They will be reviled - not just by our enemies but also by those we seek to defend.

In the past, Americans were up to such challenges. They refused to give up or to give in to those they recognized as enemies of freedom. We will soon learn whether the current generation is made of the same hardy stuff.

Clifford D. May, a former New York Times foreign correspondent, is the president of the Foundation for Defense of Democracies, a policy institute focusing on terrorism.