Fifteen years into the 21st century, it is clear that the United States faces an era full of new threats. Some are political and military. The most serious is psychological.
During this century, the United States will not dominate the world as it did during the last one. If Americans can adjust to this reality, there is hope for global stability. If we refuse — if we do not accept the relative decline in our power — our frustration may lead us to lash out in self-destructive ways.
Nations naturally rise and decline over the course of time. Those that survive the longest, like China and Iran, do so by riding the tides of history. Americans have no experience doing that. For us the tide has always been high. Over the course of the 20th century, our power grew steadily. We became accustomed to running the world. In the future, we will not run it. Nothing in our history prepares us for this looming change in our global status. We are not psychologically ready for it.
In the new world, our mightiest weapon, military power, will be steadily less valuable. A skill we have not developed, coalition-building among nations, will become the key to world power. To thrive in the 21st century, the United States needs a new set of tools. Most of all, we must recognize the reality of our changing role in the world.
History makes this difficult. It is always wrenching to lose power. Politics also stands in the way. Candidates compete with each other to promise bigger military budgets and more merciless wars. They feed the cheering fantasy that the "American century" can last forever.
Signs of the emerging new world are impossible to miss. A terror gang in the Middle East has seized territory, and we are forced to realize that despite all our military might, we cannot dislodge it without help from local partners. Russia openly defies us. Turkey, a NATO ally that was long our lap dog, ignores our pleas and goes its own way. Saudi Arabia launched a war without even consulting us.
Most challenging is our changing relationship with China. By mid-century, if not before, Americans will be faced with a reality we have never known: a rival that is more populous, richer, and more historically powerful than the United States. Our response to recent Chinese probes in the Pacific has been militaristic. It suggests that our policy toward China is stuck in the 20th-century "us-against-them" paradigm. If we pursue this policy, the long-term victor is likely to be them, not us. During the middle and later decades of this century, the United States will not be able to prevail over China in conflicts around China's borders. This may be difficult for Americans to grasp or accept.
The great security challenges of this century are global, ranging from terrorism to climate change. They can only be met by nations acting together. The United States, however, has rarely had to join coalitions of equals. We are used to telling our partners what to do. In the new age, we must persuade them and accommodate their interests. This requires willingness to compromise—something to which we are unaccustomed.
Great wars often explode at moments of tectonic geopolitical change: when rising states challenge a long-dominant power. The conflict is set off not by a challenger, but by the dominant power, which fears losing its top-dog status. Thucydides cited this as the reason for the Peloponnesian War 2,400 years ago: "It was the rise of Athens, and the fear that this inspired in Sparta, that made war inevitable."
The United States should not fear the rise of other powers. We reduce the prospect of conflict by adapting to the world as it changes. Our relative power will logically decline as other nations become richer and stronger. This historic inevitability may be a gift. A multipolar world is inherently more stable than one overseen by a single power. The United States has the tools we need for continued national success. It will be ours if we can make the psychological transition to a world we do not dominate.
Stephen Kinzer is a senior fellow at the Watson Institute for International Studies at Brown University. Follow him on Twitter @stephenkinzer.