Following the first direct talks between Russia and Ukraine after a nine-month pause, negotiators agreed to a large-scale prisoner exchange — as they have after nearly every round of talks — but little else to bridge the gap on the major issues dividing them, including a plan for postwar security in the region. There has also been no indication that Moscow has stepped back from its maximalist demands aimed at crushing Ukraine, as the country braces for what is likely to be its toughest winter yet because of relentless Russian strikes. The two-day talks in Abu Dhabi exposed a deepening...