HMS Defender. Seyran Baroyan/AFP via Getty ImagesAccording to the BBC, classified military plans were discovered behind a Kent bus stop last week.After realizing the paper's sensitive nature, a member of the public found them and sent them back.According to reports, the documents include plans for a possible UK presence in Afghanistan.Check out more stories from Insider's business page.According to BBC, an anonymous member of public discovered top-secret military documents hidden behind a bus stop last week in the British British county of Kent.According to the BBC, the documents included nearly 50 pages of PowerPoint presentations and emails.One set of documents may contain plans for a possible UK military presence to Afghanistan.Continue reading: The insane amount of money that we spend on the US Military is actually making our country less secureThe trove also contains papers that examine possible Russian reactions to HMS Defender, a British Royal Navy ship. It was a controversial vessel and provoked a diplomatic row when it passed through Ukrainian waters just off the Crimea coast.According to the Ministry of Defence, a senior employee reported that the documents were missing from their office last week.Sky News reports that the spokesperson for the department said, "The department takes security of information extremely seriously" and launched an investigation.HMS Defender, a HMS Defender-class warship, sailed near the Crimean coast of the Black Sea on Wednesday. Russia responded by sending more than 20 aircraft, two coastguard ships and two helicopters to watch the warship.Officials from the British government claim that the move was legal under international law. However, Russia insists it violated its territorial borders. The UK considers the occupation in Crimea illegal.An email with the promotion of noncommissioned officers including members of the SAS's E Squadron special forces, which contained information about the British Ministry of Defence's security flaws, was sent to the government by mistake.Business Insider has the original article.