“Americans want to believe that their country is a bastion of moral principles and that their government does not violate those values in the course of implementing the nation’s foreign policy,” Ted Galen Carpenter and Malou Innocent write in their new book. But as the United States assumed a global leadership role after World War II, a growing number of relationships were forged in which Washington’s new security partners were, to varying degrees, repressive and corrupt.

In Perilous Partners, Carpenter, a senior fellow for defense and foreign policy studies at Cato, and Innocent, an adjunct scholar at the Institute, offer case studies of U.S. engagement with dubious allies, examining the official justifications for these partnerships and assessing their credibility. They look at both the benefits and the costs in blood, treasure, and values to the American republic of more than a dozen specific associations. “We hope that such a treatment will assist both policymakers and the American people strike a proper balance in the future,” they write.

The authors begin by surveying the period when these questionable alliances first formed. “The ethical rot in U.S. foreign policy began early in the Cold War and grew worse as the rivalry with the Soviet Union deepened,” they write. With time, Washington’s actions were not just inconsistent with America’s ideals — they directly undermined them. “It is difficult to square the notion of allegiance to the values of peace, democracy, individual liberty, and the rule of law with the overthrow of democratically elected governments, the provision of financial aid and political support for corrupt autocrats, and in some cases, helping to install and sustain in power murderous sociopaths,” Carpenter and Innocent write. “Yet at times the U.S. government did all of those things.”

In examining each case study — from Latin American strongmen to South Vietnamese dictators — Carpenter and Innocent demonstrate “the acute dilemma” inherent in balancing national security with America’s values. “U.S. leaders cynically referred to some of the most corrupt and brutal dictatorships as members of the Free World, as long as those regimes cooperated with Washington’s geopolitical objectives,” they write.

Unfortunately, those coalitions did not dissolve once the Cold War ended. As the authors note, the United States strengthened its commitment to democracy and human rights throughout the 1990s. But that revival didn’t last long. “Once the United States embarked on a new crusade, targeting radical Islamist movements and regimes following the 9/11 terrorist attacks, there was a tendency to revert to old habits and cut ethical corners without sufficient reflection,” Carpenter and Innocent write. The authors acknowledge that when national survival or other vital interests are at stake, such alliances can be justified. But too often American leaders have sacrificed the moral high ground in pursuit of secondary and peripheral national interests. The authors therefore recommend an ethical pragmatism when it comes to foreign policy, outlining standards to determine when compromising American principles is necessary, when it is questionable, and when it is outright counterproductive. They propose an arm’s-length relationship with authoritarian regimes, emphasizing that the United States will gain little if it deals with the threat of terrorism in ways that routinely pollute American values.

In the end, Carpenter and Innocent offer a compelling account of perils involved in getting too close to friendly tyrants, injecting historical insight into current dilemmas in order to provide policy prescriptions for the near future. “To promote human rights in some countries and simultaneously support the world’s most savage and illegitimate autocracies may very well reflect Washington’s geopolitical preferences,” they write, “but such inconsistency also highlights an enormous discrepancy between what the U.S. government claims to do and what it actually does.”