In this report, the authors create a framework that can be used to rigorously consider the trade-offs involved in U.S. military intervention decisions following the outbreak of a war or crisis. This framework can provide a better understanding of the relationships between intervention timing, intervention size, and intervention outcomes to inform future debates about whether, when, and with what size force to undertake a military intervention.

This report analyzes the U.S. and allied campaign against the al Qa’ida–linked terrorist group al Shabaab in Somalia, examines what steps have been most successful against the group, and identifies potential recommendations. It concludes that, while al Shaba'ab was weakened between 2011 and 2016, the group could resurge if urgent steps are not taken to address the political, economic, and governance challenges at the heart of the conflict.

As the U.S. National Defense Strategy recognizes, the United States is currently locked in a great-power competition with Russia. This report seeks to define areas where the United States can compete to its own advantage. It examines Russian vulnerabilities and anxieties; analyzes potential policy options to exploit them; and assesses the associated benefits, costs, and risks, as well as the likelihood of successful implementation.

The Islamic State has lost substantial amounts of territory but continues to conduct and inspire attacks around the world. This report assesses the threat the Islamic State poses to the United States and examines strategies to counter the group and prevent a resurgence of the Islamic State or other Salafi-jihadist groups.

Given Russia’s annexation of Crimea and continued aggression in eastern Ukraine, Europe must reassess its approach to a regional security environment previously thought to be stable and relatively benign. This report analyzes the vulnerability of European states to possible forms of Russian influence, pressure, and intimidation and examines four areas of potential European vulnerability: military, trade and investment, energy, and politics.

Despite Russia’s relatively small global economic footprint, it has engaged in more interventions than any other U.S. competitor since the end of the Cold War. In this report, the authors assess when, where, and why Russia conducts military interventions by analyzing the 25 interventions that Russia has undertaken since 1991, including detailed case studies of the 2008 Russia-Georgia War and Moscow’s involvement in the ongoing Syrian civil war.

The Islamic State of Iraq and the Levant (ISIL) has recently been more successful than al Qaeda in gaining U.S. terrorist recruits. The authors undertake a demographic profile of individuals drawn to foreign terrorist organizations and find that the affiliates average terrorists recruited by ISIL is younger, less educated, and more likely to be African American/black or Caucasian/white and a U.S.-born citizen.