The Ministry of Defence (MoD) has launched a marketing campaign warning against posting potentially risky messages on social networks.
The Personal Security Online project consists of a website and a number of accompanying materials, including two videos.
In one advert, two female Navy personnel are seen disembarking from their ship for a break. One is on Twitter constantly and places her location on Foursquare.
The clip closes with the pair dancing alongside terrorists in a club, followed by the tagline: "Is it just your mates who know where you've checked in?"
Another ad focuses on the mother of an airman, who posts on Facebook he is expecting a "VVIP" visit. The mother then reports on her son's condition and his excitement around the visit.
The remainder of the video shows the mother with a terrorist drinking tea together, accompanied by the tagline: "It may not just be friends and family reading your status updates."
"Remember that there may be those who are using such sites for unsavoury reasons," the MoD said on its Personal Security Online website.
"These range from criminals looking for ways to con you or steal your identity, to those who may wish us harm."
The MoD recommended users review their privacy settings so they know who can see their data.
"You need to be aware of how much information there is online about you," the Government department added.
"Not just that which you've put there yourself, but also that which other people or organisations have put there. You need to be especially careful if you have identified yourself as being a member of the military or an MOD civilian."
The same message can apply to businesses of all kinds. There have been numerous cases in the last year where tweets or Facebook messages have landed organisations in trouble.
Last year, a Labour candidate leaked the results of her area's postal vote through Twitter. Police ended up investigating the case.
