President Obama reminded us Tuesday that "our power grows through its prudent use; our security emanates from the justness of our cause, the force of our example, the tempering qualities of humility and restraint." A week ago, in her confirmation hearings to become secretary of State, Hillary Rodham Clinton said: "America cannot solve the most pressing problems on our own, and the world cannot solve them without America. ... We must use what has been called 'smart power,' the full range of tools at our disposal."

Smart power is the combination of hard and soft power. Soft power is the ability to get what you want through attraction rather than coercion or payments. Opinion polls show a serious decline in American attractiveness in Europe, Latin America and, most dramatically, the Muslim world.

The resources that produce soft power for a country include its culture (when it is attractive to others), its values (when they are attractive and not undercut by inconsistent practices) and policies (when they are seen as inclusive and legitimate).

When poll respondents are asked why they report a decline in American soft power, they cite American policies more than American culture or values. Because it is easier for a country to change its policies than its culture, this implies that Obama will be able to choose policies that could help to recover some of America's soft power.

Of course, soft power is not the solution to all problems. North Korean dictator Kim Jong Il likes to watch Hollywood movies, but that is unlikely to affect his nuclear weapons program. And soft power got nowhere in attracting the Taliban government away from its support for Al Qaeda in the 1990s. That took hard military power in 2001. But other goals, such as the promotion of democracy and human rights, are better achieved by soft power.

A little more than a year ago, the bipartisan Center for Strategic and International Studies' Commission on Smart Power concluded that America's image and influence had declined in recent years, and that the U.S. had to move from exporting fear to inspiring optimism and hope.

The commission was not alone in this conclusion. Defense Secretary Robert M. Gates has called for the U.S. to commit more money and effort to soft-power tools, including diplomacy, economic assistance and communications, because the military alone cannot defend U.S. interests. He pointed out that military spending totals nearly half a trillion dollars annually -- excluding Iraq and Afghanistan -- compared with a State Department budget of $36 billion. In his words: "I am here to make the case for strengthening our capacity to use soft power and for better integrating it with hard power."

The Pentagon is the best resourced arm of the government, but there are limits to what hard power can achieve on its own. Promoting democracy, human rights and the development of civil society are not best handled with the barrel of a gun. The effects of the 9/11 terrorist attacks threw America off course. Terrorism is a real threat, but over-responding to the provocations of extremists does us more damage than the terrorists ever could. Success in the struggle against terrorism means finding a new central premise for U.S. foreign policy to replace the "war on terror." A commitment to providing for the global good can provide that premise.

America can become a smart America -- a smart power -- by again investing in global public goods, providing things people and governments of the world want but have not been able to get in the absence of leadership by the strongest country. Development, public health and coping with climate change are good examples. By complementing U.S. military and economic might with greater investments in soft power, and focusing on global public goods, the U.S. can rebuild the framework that it needs to tackle tough global challenges.

Style also matters. In 2001, columnist Charles Krauthammer argued for what he called "a new unilateralism," which recognized that the United States was the only superpower and was so strong that it could decide what was right and expect others to follow because they had little choice. But this style turned out to be counterproductive. Insensitivity to style and the perception of others can undercut soft-power efforts.

Obama faces a difficult international environment, but previous presidents have managed to employ hard, soft and smart power in equally difficult contexts. In 1970, during the Vietnam War, America was viewed as unattractive in many parts of the world, but with changed policies and the passage of time, the United States managed to recover its soft power. It can happen again.

Joseph S. Nye Jr. teaches at Harvard and is the author of "The Powers to Lead." He is the coauthor, with Richard Armitage, of "A Smarter, More Secure America," the CSIS commission report on smart power.