A new study urges the Navy to create an office to guard against unexpected threats, perhaps the toughest and biggest challenge facing the Pentagon, but fiscal pressures could present a hurdle to standing up any new organization. The report, issued by the National Academy of Sciences' Naval Studies Board, calls on Chief of Naval Operations Adm. Jonathan Greenert to form a "surprise-mitigation office," proposing several ways to do it. A Navy spokesman said Greenert, who is traveling abroad, has not...