Read an excerpt of Foreign Policy Begins at Home.

The biggest threat to the United States comes not from abroad but from within. This is the unexpected message of Council on Foreign Relations President Richard N. Haass in Foreign Policy Begins at Home: The Case for Putting America's House in Order.

"Many of the foundations of this country's power are eroding," he warns. "The effect, however, is not limited to a deteriorating transportation system or jobs that go unfilled or overseas owing to a lack of qualified American workers. To the contrary, shortcomings here at home directly threaten America's ability to project power and exert influence overseas, to compete in the global marketplace, to generate the resources needed to promote the full range of US interests abroad, and to set a compelling example that will influence the thinking and behavior of others."

A rising China, climate change, terrorism, a nuclear Iran, a turbulent Middle East, and a reckless North Korea all present serious challenges. But, Haass argues, U.S. national security depends even more on the United States addressing its crumbling infrastructure, second-class schools, outdated immigration system, and burgeoning debt, something that will require controlling entitlements rather than just raising taxes and cutting discretionary spending.

Haass rejects both isolationism and the notion of American decline. But he contends the country is underperforming at home and overreaching abroad. He argues that the United States must sharply limit its role in humanitarian interventions and in wars of choice designed to remake other societies, as was tried unsuccessfully in Iraq and Afghanistan. Instead, it should emphasize maintaining the balance of power in Asia, advancing North American economic integration and energy self-sufficiency, and promoting collective responses to global challenges.

The world is no longer dominated by one or more superpowers. Instead, the paramount feature of international relations in the first half of the twenty-first century is nonpolarity; power has been diffused, spread among an enormous list of entities capable in their own right to exert their influence. In addition to traditional nation-states, there are many other entities active in the political sphere, whether global (UN, World Bank), regional (European Union, NATO, Arab League), commercial (JPMorgan Chase, Exxon Mobil), disruptive, or altruistic. This world is relatively forgiving, however, with no great rival directly threatening American interests.

How long this strategic respite lasts and how well the nation continues to fare on the global stage, according to Haass, will depend largely on whether the United States puts its own house in order.

Educators: Access Teaching Notes for Foreign Policy Begins at Home.