Is America Reverting to Isolationism?

The first debate between the Republican Party's candidates for next year's US presidential election revealed major schisms over foreign policy. While former US Vice President Mike Pence and former US Ambassador to the United Nations Nikki Haley defended America’s support for Ukraine in Russia's war of aggression, Florida Governor Ron DeSantis and businessman Vivek Ramaswamy expressed skepticism. Former President Donald Trump — the unquestioned front-runner — skipped the event, but he, too, has objected to US involvement in that conflict.

Polls show that rank-and-file Republicans are as divided as the candidates. That raises concerns that if an isolationist Republican wins in 2024, it could mark a turning point for the US-dominated international order established at the end of World War II.

Historically, American public opinion has oscillated between extroversion and retrenchment. Having witnessed the tragic consequences of the isolationism of the 1930s, President Franklin D. Roosevelt launched the process that culminated in the creation of the Bretton Woods institutions in 1944 and the United Nations in 1945. President Harry Truman's post-war decisions then led to permanent alliances and a continual US military presence abroad. The United States invested heavily in European reconstruction through the Marshall Plan in 1948, created NATO in 1949, and led the UN coalition that fought in Korea in 1950.

These actions were part of a realist strategy to contain Soviet power. But containment was interpreted in various ways, and Americans later had bitter, often partisan debates over interventions in developing countries like Vietnam and Iraq. Still, while the ethics of intervention were called into question, the value of sustaining a liberal institutional order was much less controversial. As the American theologian Reinhold Niebuhr once observed, the "fortunate vagueness" of liberal internationalism had saved it from succumbing to ideological rigidity.

The liberal international order thus enjoyed broad support in US foreign-policy circles for decades after WWII. But in the 2016 presidential election, Trump's argument that the post-1945 alliances and institutions had benefited others at America's expense resonated strongly with many voters. To be sure, his populist appeal rested on more than an attack on US foreign policy. He also tapped into widespread anger over the economic dislocations caused by globalization and the post-2008 Great Recession, and exploited polarizing cultural changes related to race, the role of women, and gender identity. But by blaming economic problems on "bad trade deals with countries like Mexico and China and on immigrants competing for jobs," Trump successfully linked nativist resentment to US foreign policy....