soft power
n. Power based on intangible or indirect influences such as culture, values, and ideology.
The US's best soft power analyst is Harvard's Kennedy School dean Joseph Nye, who defines the concept as "co-opting people rather than coercing them". For Nye the essence of soft power lies in values — "in our culture and in the way we handle ourselves internationally". It's about creating a sense of legitimacy for a nation's international aims. Soft power is, of course, both easy and hard for the US. It is the model and anti-model, the focus of imitation and the target of hatred. Nye nominates Canada, the Netherlands and the Scandinavian countries as states whose political influence is greater than their hard power would permit. The explanation lies in their astute manipulation of soft power.
—Paul Kelly, “Soft option for hard heads,” The Weekend Australian, June 08, 2002
1990 (earliest)
But if the United States were to follow policies that cut domestic consumption by the two percent of GNP by which it rose in the past decade, the richest country in the world could afford both better education at home and the international influence that comes from an effective aid and information program abroad. What is needed is increased investment in "soft power," the complex machinery of interdependence, rather than in "hard power" — that is, expensive new weapons systems.
—Joseph S. Nye, “The misleading metaphor of decline,” The Atlantic, March 01, 1990
The Joseph Nye mention in the first citation is not only the "best soft power analyst" (an assertion I found in many of the citations I looked at), but he was also the first, having coined the term in the early 90s (see the earliest citation).