US officials are working to establish the source of a leak of dozens of secret documents relating to the war in Ukraine.<br /><br />The Pentagon has referred the matter to the Department of Justice, which has opened a criminal investigation.<br /><br />Documents appeared on social media websites in early March.<br /><br />According to Reuters, whose journalists have reviewed more than 50 of the documents, the intelligence purportedly revealed details of Ukrainian military vulnerabilities and information about allies.<br /><br />The documents had not drawn much attention until a New York Times report on Friday, 7 April.
