text:  And we preview the stakes for NATO leaders landing in Washington for this week's Summit of the Alliance. First, the news. Live from NPR News in Washington, I'm Jack Spear. Leaders from NATO countries are descending on Washington, D.C., ahead of a three-day summit, which starts tomorrow. As NPR's Jackie Northam reports, it's the 75th anniversary of NATO's founding, but ongoing concerns about Ukraine and American politics are hovering over the event.