In the sweltering summer of 1944, two months after ­D-­Day, British and Soviet diplomats joined the Americans in Washington to discuss how the three powers that were shaping the world could preserve the peace in the years to come. Their answer was a grand body of member ­states—­the United ­Nations—­with responsibility for peace and security falling to a “Security Council.” This elite club would have five permanent ­members—­the United States, Britain, and the Soviet Union, plus France and ­China—­with the power to veto any proposed resolution, and 10 other members elected on a rotating basis from the galaxy of states. In the 65 years since its creation, the Security Council has frustrated those who thought it would mean an end to violent conflict, disap­pointed many who assumed that nations would actually unite, and alienated the American Right, which considers it a constraint on U.S. power. Yet the fact remains that the Security Council is a critical venue for international ­dialogue.

In Five to Rule Them All, David L. Bosco, a professor of international politics at American University, guides readers through the history of the Security Council, from its first peacekeeping endeavor in the Congo, through the Cold War, to the present. This fine book blends insight into great-power politics with saucy anecdotes, including an account of the ­American-­led sally to a famous New York City nightclub, Billy Rose’s Diamond Horseshoe, designed to ease tensions during those 1944 negotiations. The only wish a reader might have is for more discussion of the current challenges that face the Security ­Council.

Bosco highlights the Security Council’s suc­cesses, such as the tireless work of then–secretary-­general Javier Pérez de Cuéllar and his team to end the ­Iran-­Iraq War in 1988. He is also frank about the body’s failures, among them its inability to facilitate peace in the Middle East and to stop the 1994 genocide in Rwanda and the Srebrenica massacre, in Bosnia, in 1995. He is astute about the impact of seemingly subtle decisions by the Security Council, as when the Soviet Union’s permanent seat was transferred to Russia in 1989 “with scarcely a whisper of debate.” In rushing through this transition, Bosco writes, the Security Council missed an oppor­tunity to realign power that “might have allowed adjustment to reflect new realities and refresh the council’s legitimacy with the rest of the world,” though, in keeping with the ­non-­prescriptive nature of the book, he doesn’t say what that realignment ought to have looked ­like.

Today, we have moved beyond the ­post-­Soviet moment. America is no longer the sole super­power, yet it has no equal. As Bosco notes, large ­non-­Western blocs of nations have consistently criticized the Security Council for paying too little attention “to what many poor nations saw as the root cause of much conflict: disparities in econ­omic development.” Today these objections are heard less often, in part because the loudest critics, including India and Brazil, have gained enough power to pursue their own interests aggressively. But the Security Council’s relevance and legitimacy are still in question in two key ­ways.

First, the informal arrangement that allowed the Security Council to intervene in and mitigate violent conflict over the last two decades in ­Timor-­Leste, Sierra Leone, Liberia, Haiti, Kosovo, Guatemala, and elsewhere is increas­ingly unstable. In the past, permanent members would make the decision to inter­vene, others (Japan and Germany) would pay, and a third group (often including India, Pakistan, and Bangladesh) would provide troops. It makes less sense, with each passing year, to the Japanese and Germans to foot the bills without a guaranteed say in the decisions, or for India, which has more than 15 percent of the world’s population, to assume risks without a share of ­control.

Second, the role of the Security Council in dealing with problems that lack clearly defined ­borders—­climate change, resource scarcity, terrorism, nuclear proliferation, ­sub­national ­violence—­is uncertain. President Barack Obama’s decision to chair a recent Security Council summit on nuclear ­non­proliferation signals that the body has a role in dealing with this issue, but the precise nature of that role remains ­unclear.

Hovering over Bosco’s book is an abiding sense of the failure of the great powers to recognize change, combined with a quaintly desperate desire to preserve privileges and rights of a bygone era. Set against this is the remarkable success of the Security Council in preventing conflict among the great powers; its exis­tence accounts, at least in part, for the fact that we have avoided another world war. Unless the five permanent members can find a pathway to sharing and extending their power, the legiti­macy of the Security Council will continue to ­erode.