The Obama administration is weighing a range of aggressive responses to Russia’s alleged violation of a Cold War-era nuclear treaty, including deploying land-based missiles in Europe that could pre-emptively destroy the Russian weapons. This “counterforce” option is among possibilities the administration is considering as it reviews its entire policy toward Russia in light of Moscow’s military intervention in Ukraine, its annexation of Crimea and other actions the U.S. deems confrontational in Europe and beyond.