If re-elected, would Donald Trump end U.S. support for Ukraine? He certainly sounds as if he would. On the campaign trail, he routinely describes Ukraine as a burden to the U.S. and declares his eagerness to see the war end, which he promises to achieve through negotiations in a mere 24 hours. Trump has also made clear his admiration for Vladimir Putin and dismissive attitude toward the European Union. Many observers worry that once back in office, he would condone, tacitly or even directly, Russia’s efforts to dominate Ukraine. But it wouldn’t be an easy move for Trump to make,...