But over time, the impact of World War II, and fear of the Soviet Union, largely overcame these anxieties, and Cold War conservatism was born. To justify America’s struggle against virulently anti-democratic powers, conservatives began defining America’s global role ideologically. The United States would lead the free world against its despotic foes.

The narrative created by World War II—of America heroically joining its allies to save the world from Nazi tyranny—countered conservative fears about binding commitments. And, Taft notwithstanding, a 1948 poll found that two-thirds of Democrats and Republicans alike supported the creation of NATO. “Politically speaking, isolationism has disappeared as far as mutual treaties against aggression are concerned,” explained the pollster George Gallup. Not only did most conservatives support NATO, by the 1950s most supported the Eisenhower administration’s effort to replicate it in regional pacts like SEATO (the Southeast Asian Treaty Organization) and CENTO (the Central Treaty Organization). Cold War conservatives still took a dim view of the United Nations, which, in their minds, sapped America’s sovereignty while amplifying the voices of its foes. But they became staunch defenders of America’s military alliances. Sovereignty was important, but defending the nations menaced by Soviet communism came first.

The need to sustain alliances also reshaped views of foreign aid. Taft not only opposed NATO—along with business groups like the Chamber of Commerce and the National Association of Manufacturers, he also opposed the Marshall Plan on the grounds that, in order to pay for it, the government might raise taxes. But by the 1950s, conservatives were willing to ship money overseas if it strengthened America’s anti-communist allies. In his book The Conscience of a Conservative, Barry Goldwater, while decrying the fact that, “increasingly, our foreign aid goes not to our friends, but to professed neutrals” defended delivering “military and technical assistance to those nations … that are committed to a common goal of defeating world communism.”

Anti-communism also contributed to conservatives’ embrace of free trade. Since the 19th century, the Republican Party had championed protectionism. Republicans had overwhelmingly supported the Smoot-Hawley bill that in 1930 raised tariffs on 20,000 types of imported goods. As late as 1946, notes the Dartmouth economist Douglas Irwin, author of Clashing over Commerce: A History of U.S. Trade Policy, congressional Republicans almost torpedoed the negotiations that led to the tariff-reducing General Agreement on Tariffs and Trade.

In the 1950s and 1960s, however, the GOP moved decisively in favor of free trade. Partly that’s because American businesses—which were becoming increasingly multinational—wanted lower trade barriers so they could take advantage of markets abroad. The United States had also finished World War II in such a commanding economic position that few Americans worried foreign competition would threaten their jobs. But the shift was also the result of the Cold War. Conservatives as well as liberals argued that by exporting goods to the U.S., America’s European and Asian allies could build the economic strength necessary to contain the U.S.S.R. The struggle against communism also made protectionism ideologically uncomfortable. If leading the free world meant championing the free market against Soviet-style government planning, then it was hard to justify government barriers to free trade.