evidence: Today, the world is facing another challenge. Russia has seized unilateral control of the Kerch Strait, and the West has done nothing. This may tempt Putin—who is already massing forces—to seize even more Ukrainian territory, attempt to subvert the Ukrainian presidential election, or both. [...] By firing on the Ukrainian naval ships in international waters, by treating Ukraine’s sailors as civilians rather than members of a sovereign state’s armed forces, and by basing these actions on its claimed annexation of Crimea and its territorial waters, Russia violated international law, the laws of armed conflict, and a 2003 bilateral agreement in which Russia and Ukraine agreed to share sovereignty and control over the Sea of Azov and the Kerch Strait. Russia argues that it now has sole sovereignty over the strait; most of the world disagrees. Ukraine will not lightly abandon its right to move naval vessels through the Kerch Strait and other territorial waters around Crimea. Russia is likely to respond as aggressively as it did in November, worsening the risk of further conflict. But there are several other factors heightening the crisis.