The Islamic State faces serious barriers to growth. It has earned an array of capable adversaries, including the United States, Iran, Russia, and the Kurds, as well as the Iraqi government and the Syrian regime. Military eforts against the Islamic State have steadily intensified with the accumulation of intelligence against it, which has facilitated targeting, and with greater coordination among and operational competence of its diverse enemies. Its territorial losses and internal strains will erode its ability to recruit. These challenges, however, will likely prompt increased attacks in Europe, Russia, Turkey, and possibly Lebanon and Jordan. Rivalry between jihadi groups could also spur attacks by alQa`ida and its afliates. An eclectic targeting strategy combined with an ability to motivate lone wolves and returnees suggest that an impenetrable defense will be difcult to mount. Yet the actual threat, especially to the United States, is relatively manageable. Despite this reality, U.S. political dynamics have generated a nationwide anxiety that could contribute to violence. In Europe, where the risks are higher, the prospects for social cohesion are bleaker.