The Ministry of Defence has released an updated series of wartime public information films to warn people of the dangers of social media.
In the videos posted on YouTube, the 70-year-old slogan "careless talk costs lives" is being applied to members of the armed forces and their families that use Facebook and Twitter.
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The MoD is concerned that posting to social media sites may inadvertently give away planned operations, movements of troops and aircraft or the location of ships.
The YouTube campaign is aimed at raising awareness about the risks of sharing too much information online.
One video shows a mother of a soldier updating her status on Facebook with details of her son's whereabouts. The caption reads: "It may not just be friends and family reading your status updates."
Alongside the video campaign, new recruits will be taught to modify their social media habits as part of their basic training.