The U.S. Air Force has decided to scrap its Northrop Grumman Corp high-altitude unmanned surveillance plane program and keep its Cold War-vintage U-2 spy planes flying into the 2020s, according to a government official and a defense analyst. Loren Thompson, chief operating officer of the Virginia-based Lexington Institute, said the Air Force decision was based on the cost of the RQ-4 Global Hawk unmanned planes, and said the service would investigate using a marine version with different sensors that Northrop is developing for the Navy. The Navy is proceeding with its plans to buy 68 of that version of the...