In international relations, the term smart power refers to the combination of hard power and soft power strategies. It is defined by the Center for Strategic and International Studies as "an approach that underscores the necessity of a strong military, but also invests heavily in alliances, partnerships, and institutions of all levels to expand one's influence and establish legitimacy of one's action."
Joseph Nye, former Assistant Secretary of Defense for International Security Affairs under the Clinton administration and author of several books on smart power strategy, suggests that the most effective strategies in foreign policy today require a mix of hard and soft power resources. Employing only hard power or only soft power in a given situation will usually prove inadequate. Nye utilizes the example of terrorism, arguing that combatting terrorism demands smart power strategy. He advises that simply utilizing soft power resources to change the hearts and minds of the Taliban government would be ineffective and requires a hard power component. In developing relationships with the mainstream Muslim world, however, soft power resources are necessary and the use of hard power would have damaging effects.
According to Chester A. Crocker, smart power "involves the strategic use of diplomacy, persuasion, capacity building, and the projection of power and influence in ways that are cost-effective and have political and social legitimacy" – essentially the engagement of both military force and all forms of diplomacy.