The US Justice Department has opened an investigation into the leaking of dozens of classified American Defence Department documents on social media.It is the biggest leak of secret American information on the war in Ukraine since Russia’s full-scale invasion 14 months ago.The maps, charts and photographs – some of them marked “top secret” – paint a detailed picture of the war in Ukraine.The documents also reveal of details of Washington’s other allies, from Israel to South Korea, including internal debates those countries are having about Ukraine and other sensitive issues.Pentagon officials are quoted as saying the documents are real.