Reframing Isolationism: A Comparative Analytical Framework for Contemporary U.S. Foreign Policy

This paper develops a methodological framework for systematically tracing U.S. isolationism, interventionism, and internationalism across presidential administrations in the interwar and post-Cold War eras (1921–1945; 1989–2021). The aim is to offer a novel approach to comparative analysis of U.S. foreign policy over time. Because the United States continues to anchor security in the Asia-Pacific, Europe, and West Asia/North Africa, its willingness to act – or to abstain – has implications far beyond its borders. Recent foreign policy choices, particularly under the Trump administration, have also revived debates about U.S. isolationism and its contemporary meaning. In this context, systematically observing when the United States responds to crises, and when it does not, becomes especially important. The framework treats core policy “ingredients” – non-interventionism, unilateralism, and multilateralism – as continuous, coexisting dimensions that vary in degree over time. It recasts U.S. isolationism as an operationalized policy-response stance measured from observed crisis behavior (International Crisis Behavior v16, supplemented by archival sources), producing comparable isolationism scores across interwar and post-Cold War administrations, independent of prevailing period narratives. The framework applies explicit selection criteria to ICB cases to identify isolationist responses, and an index quantifies isolationism by weighting crisis relevance, response intensity, and the proportion of isolationist responses relative to the total number of crises in each presidency. The empirical analysis demonstrates the analytical utility of both the framework and the revised concept. It (i) confirms that isolationist tendencies coexist with active engagement; (ii) finds that isolationism is lower in the interwar and higher in the contemporary era than conventional accounts suggest; and (iii) shows that many interwar nonresponses involved low-salience crises, which helps explain why aggregate isolationism levels converge across periods once relevance is considered. Interpreting these numerical results in historical context reveals recurrent patterns: U.S. isolationism covaries with conservative prudence combined with foreign-policy experience among key decision-makers, as well as with exogenous shocks.