The next president should move swiftly to reassure allies that the U.S. nuclear guarantee remains credible—or risk rapid nuclear proliferation. One important consequence of the fraying of U.S. alliances over the last few years is the reemergence of concern in allied capitals about the credibility of the U.S. nuclear guarantee. …

Latest escalation comes amid increased Turkish military involvement in a region stretching from Syria to the Caucasus and the Mediterranean. Russia and Turkey are two sides of the same coin. They are both heavily involved in some of the world’s most significant ongoing conflicts including in Libya, the Caucasus and …

American drones and U.S. allies killed several Qaeda leaders and operatives in the past week. But the organization has “ingrained itself in local communities and conflicts,” according to the U.N.