Commerce has changed the ethics of citizenship and the incentives for national service. America now buys private contractors - we used to call them mercenaries - to do the country's fighting.

Desert Storm created the pattern for the American way of war that eventually prevailed in Kosovo. America learned from Vietnam that unilateral use of force eventually forfeits international legitimacy and domestic support. Desert Storm demonstrated the political necessity of coalition warfare.

America owed its military renaissance in the 1980s and 1990s to Vietnam. Veterans like Norman Schwartzkopf, Colin Powell, Alfred Grey, Charles Krulak, and Wesley Clark returned home angry and ashamed at their defeat and rebuilt all-volunteer, professional armed forces from the ground up.

Affirming belief that America is an exceptional nation has become a test of patriotism in American politics.

America is exceptional in combining standard great-power realism with extravagant idealism about the country's redemptive role in creating international order.

I remember the intellectual fashion for American decline in the 1970s. There was the stunning defeat of the U.S. in Vietnam , rioting in Detroit and Newark that suggested the social fabric was coming apart, talk of Rust Belt America unable to compete with the Japanese, and a sense the Russian bear was on the march.

I remember the intellectual fashion for American decline in the 1970s, ... There was the stunning defeat of the U.S. in Vietnam , rioting in Detroit and Newark that suggested the social fabric was coming apart, talk of Rust Belt America unable to compete with the Japanese, and a sense the Russian bear was on the march.