For the past 8 years, two U.S. administrations, the United Nations (UN), and numerous foreign governments have sought to end the catastrophic war in Syria and reach a negotiated political settlement to the conflict. Their efforts have repeatedly been complicated, even thwarted, by the highly contested and violent politics underlying the conflict, the sheer number of conflict actors inside and outside of Syria, and those actors' diverse and often irreconcilable objectives.Many of the complications for U.S. policy have stemmed from the need for policymakers to focus on three separate but intertwined dimensions of the Syrian conflict, even while policy options to deal with one dimension of the conflict had significant but often unpredictable effects on the others. The first dimension has been the campaign to deal an enduring territorial defeat upon the so-called Islamic State (IS), an element of U.S. policy that enjoyed near unanimous international consensus and adequate means to accomplish the task. The second is the central conflict between the Bashar al-Asad regime and its opponents, an existential power struggle that drew in multiple foreign powers and yielded nearly unimaginable destruction of Syrian property, infrastructure, and lives. And the third is the strategic challenge of Iran and its drive to eliminate U.S. influence in the Middle East.As the United States and other parties sought to navigate these three dimensions of the conflict, a set of paradoxical challenges-conundrums-emerged and, in some cases, made the situation in Syria even more intractable and a solution on terms favorable to U.S. national security even more elusive.This paper discusses five such conundrums. The first is that military, political, and economic pressure on the Asad regime, a principal feature of U.S. and Western policy, in many ways exacerbated problems for Syrian civilians, the Syrian opposition, and Syria's neighbors without yielding political concessions or reforms to the nature of Syrian governance. The second involves the Syrian opposition-though highly fragmented save for most extremist elements and thus an ineffective force for driving political change in Syria, the United States nonetheless continued to accord it considerable international support and legitimacy. The third conundrum deals with the challenges of balancing the U.S. relationship with Turkey, a North Atlantic Treaty Organization (NATO) ally, while simultaneously working with a Kurdish-led militia viewed by Turkey as a national security threat. The fourth centers on Russia's involvement in Syria and, specifically, the contradictory need for the United States and Russia to work together in Syria even while the two countries hold opposing views on a continued role for Bashar al-Asad in Syria's governance. And the fifth conundrum is that foreign interventions in the Syrian conflict, including those designed to counter the Asad regime's brutality and hasten a resolution of the conflict, may actually have made the war longer and bloodier, particularly for civilians. This is consistent with the historical experience with foreign intervention in civil wars elsewhere.At the end of the day, foreign involvement in such a complex and volatile situation as Syria yields, almost inevitably, unpredictable consequences. But many of the negative consequences of the Syrian conflict were actually predictable, particularly Asad's brutal reaction to the uprising, his refusal to yield to pressure, Iran and Russia's support for the regime, and the potential for foreign intervention to exacerbate the situation for Syrian civilians. Taken together, the consequences-both predictable and unpredictable-may ultimately prove to outweigh the benefits of involvement.