Why is America Addicted to Foreign Interventions?

U.S. Army Reserve Spc. Christopher Landon, a motor transport operator assigned to the 182nd Transportation Company, fires an M240B machine gun as part of Operation Cold Steel II

The United States engaged in forty-six military interventions from 1948–1991, from 1992–2017 that number increased fourfold to 188.

At a time when the United States is preparing to increase Pentagon spending and escalate troop deployments overseas, an analysis of U.S. military interventions since the country’s founding highlights two important and related dynamics.

First, the empirical distribution of military interventions––that is, the deployment of U.S. armed forces to other countries––is not evenly distributed; and in fact is highly skewed, in terms of frequency, to favor the historical period following the end of the Cold War (1991).

Second, U.S. military interventions since WWII have only rarely achieved their intended political objectives. That is, the United States has lost more than won; and when it has “won,” it has generally won at a cost far in excess of what would have been considered reasonable prior to the intervention.

This leads to an important puzzle: if U.S. military interventions are failing more often, what accounts for the dramatic increase in their use since 1991?

Basic Statistics

If we look at the distribution of the 392 U.S. military interventions since 1800 reported by the Congressional Research Service in October 2017 by fifty-year increments, the data show a dramatic increase: from 1800–1849 there were thirty-nine interventions; forty-seven from 1850–1899; sixty-nine from 1900–1949; 111 from 1950–1999; and 126 from 2000–2017—a period of only seventeen years as compared to fifty years in the other periods.

As these data reveal, the rate of intervention across time is not monotonic, but jumps during the two world war periods (1917–18), as well as the Cold War (1948–91). One implication being that the world wars forced the United States into a permanently international posture, and at the same time, as a consequence, resulted in the conscious development of reach: the raw and almost unique capacity among peer competitors to rapidly move armed forces across the globe and support them during sustained offensive operations.

If we further refine the data to compare Cold War and post–Cold War intervention rates, something truly striking emerges: while the United States engaged in forty-six military interventions from 1948–1991, from 1992–2017 that number increased fourfold to 188.

These statistics introduce two important puzzles. First, why would military interventions rise at the same time success in military interventions has been declining? Second, why would military interventions increase after the Cold War, when both an ideological rationale for interventions (say, to rescue peoples in danger of falling into a Soviet, and by extension, authoritarian, orbit) and a material existential threat to U.S. national security (no more dominoes, a reduced threat of deliberate thermonuclear war) had declined? In other words, if the United States only intervenes with armed force when its vital interests are at stake, why intervene more often when there are arguably fewer vital interests at stake? The answer is that Washington too often intervenes militarily when it should not—and U.S. security and prosperity have both suffered as a result.

Winning at Losing

Since 1950, strong actors in asymmetric conflicts (not limited to, but certainly including the United States) have lost a majority of fights with nominally much weaker adversaries (up until 1950 strong actors had won a majority of such fights). As Ivan Arreguín-Toft revealed in his 2005 book, How the Weak Win Wars, large actors like the United States beat small actors such as Vietnam 88 percent of the time from 1800–49; and their chances of victory declined from there. They won 80 percent of their conflicts from 1850–99, but only 65 percent from 1900­–49. For the last period, 1950–98, success proved elusive. Strong actors—including the United States and Soviet Union, the two so-called ‘superpowers’—lost more wars than they won: losing 45 percent of the wars they fought.

An important theoretical contribution related to the above puzzles includes T.V. Paul’s (1993) and my own on time horizons as a rationalist explanation for war (2007). Paul’s work engaged the puzzle of why weak actors initiate armed conflicts with much stronger adversaries. Paul demonstrated that one answer to the question of how a rational actor might pick a fight with a much stronger adversary had to do with time horizons: often calculations of net benefit involve very short term assessments. If time is extended, the likelihood of net benefit plummets. Thus, it may be that something structural in U.S. calculations tends to concentrate assessments of risk and benefit into short time horizons, explaining both unwarranted optimism and a high failure rate. My work on time horizons demonstrated that Paul’s conjecture was correct: if two rational actors come to a conflict of interests with very different valuations of time-to-objective, they may find themselves escalating to unwanted war which in retrospect appears irrational.

A Nonthreatening Environment