Washington’s foreign-policy circles clearly find it fashionable to talk about pressing the “reset” button on international relations. The impulse is understandable. Every new leader dreams of shaping a new era in his own image.

But the technological metaphors miss their mark. The world isn’t a PC, much less a sleek and trendy iPad. America’s search for a simple restart is destined to fail. The legacy of history resists being abandoned as easily as a software application is “exited.” Only the naive can manage to think otherwise for very long.

Meanwhile, the world is waiting for Washington to acknowledge its strategic responsibilities. America’s liberal and democratic ideals are the foundation of today’s international order. Since World War II, the United States has been the world’s defining ideological, economic, scientific, strategic, and cultural force.

Today, that order is under attack. First, there are the populist voices that have risen against our free market economy since the start of the current economic crisis. Their agenda is to alter our economic system — they want to alter the consensus from limited state presence and individual risk-taking, to greater state intervention, more public authority, and less individual freedom.

The second threats are the rising nations that feel that the current distribution of world power is unjust. They respond by undermining the policies of those they consider to be their rivals. I’m referring primarily to Russia and China, but also to populist regimes like Hugo Chávez’s Venezuela.

Third, there are the states and stateless forces that are trying to provoke a revolutionary change to the international system. Here, we can include nations like Iran and groups like al Qaeda.

The United States and its allies have all the tools at their disposal to defeat our shared enemies. Success will depend on three basic commitments: American leadership, a stronger Europe, and a common transatlantic vision.

Unfortunately, we have recently been witnessing the opposite: an internationally reluctant American president, a Europe which is mired in its own problems, and an eroded Atlantic bond.

It begins with the man in the Oval Office. When Barack Obama was elected, much of the world imagined that a change in attitude in the White House would translate into a closer and deeper relationship with Europe. Indeed, 80 percent of Europeans had said they would have voted for Obama had they been able to do so.

Those Europeans have watched as Obama has given special attention to Moscow and only a lukewarm reception to his closest allies. Today, the growing perception among European elites is that the U.S. president is not interested in Europe at all. Many of those elites instead believe that, as president, Obama is mainly concerned with improving America’s image in the Muslim world.

Europe is concerned because America’s new foreign policy seems to suggest a casual disregard of America’s closest traditional allies. Europeans have closely been following America’s friction — if not yet open dispute — with Israel, its staunchest ally in the Middle East. It’s not that Europeans have suddenly become pro-Israel. It’s because we feel it fits a larger pattern — a pattern that is especially unsettling when seen in light of Washington’s efforts to reach out to dubious regimes like Iran.

Of course, Europeans wouldn’t be so concerned about Obama if they enjoyed stronger political leadership themselves. Unfortunately, Europe’s material achievements of the past half-century have not translated into a greater ability to shoulder global responsibilities. In light of the economic crisis, that’s not likely to change anytime soon. Europe will again be involved with solving its own parochial problems.

The persistent transatlantic tension has no doubt affected our common projects. Take Afghanistan, for instance. The European public has had a difficult time coping with the presence of European NATO troops, especially as the fight has intensified in recent years. European leaders should make a clearer case for the necessity of the fight against al Qaeda. But public doubts are also fueled by the fact that the United States is itself seemingly getting ready to leave.

American exhaustion is understandable. But it’s still a mistake. Nobody is prepared to take America’s place as leader of the free world. Those who defend the virtues of a multipolar world, in which the United States is just another country, will soon find themselves in a nonpolar universe that is spinning out of control. Russia will happily reclaim its sphere of influence in Eastern Europe; a nuclear Iran will become the new hegemon in the Persian Gulf; global jihadists will be emboldened. Meanwhile, a more economically reticent (or protectionist) America will endanger any short-term recovery of the global economy and give new impetus to the anti-capitalist axis that stretches from Beijing to Tehran to Caracas.

These risks are avoidable, but only if the West — and Washington above all — has a clear vision of what it wants to achieve. The first priority should be to recuperate trust in the economic system, without which sustainable growth is impossible. The answer for private indebtedness should not be to raise the level of public indebtedness. The world had enough of socialism in the 20th century. We must learn from those mistakes.

Second, we have to refurbish the cornerstone institutions of our transatlantic alliance, starting with NATO. The organization needs to adjust to the age of jihadi terrorism. I have long advocated for NATO to assume a transatlantic component of homeland security. Furthermore, NATO should open its doors to those democratic countries that are willing and able to make a contribution to collective security, from Japan to Israel.

Third, America and Europe need to strengthen their economic ties. It is time for a fully integrated, 100 percent barrier-free, transatlantic economy. European and American citizens would benefit from increased trade and investment, strengthened competition, and greater innovation.

Finally, we have to commit to defending our values. President George W. Bush’s “freedom agenda” may have been unpopular, but it bore a central truth: America is the world’s de facto defender of liberty.

America should be proud of its identity, as should its allies. On all the critical questions of modern life — economics, education, justice, and culture — it’s the West that holds the flag of progress, freedom, and security. People from Manhattan to Kandahar, from California to Iran, are depending on us to hold that flag aloft. Obama’s administration, whatever its talk of strategic “resets,” would do well not to forget that.

Editor’s note: This text is adapted from a speech, “Resetting the World,” delivered by Mr. Aznar at the Transatlantic Center of the Johns Hopkins University.