WASHINGTON: The United States has an updated rendition for foreign visitors of the expression "Loose Lips Sink Ships" that was used to warn its citizens against unguarded talk during World War II. Apparently, loose quips from tweeting 21st century tourists are as dangerous. Two European tourists to America found out the hard way that jokes on Twitter is no tittering matter for US security officials. They were detained on arrival at the Los Angeles International airport last week and deported after one of them was said to have tweeted that he was going to "destroy America" during the trip. They insisted that the expression is British slang for partying. US Homeland Security officials were unimpressed - or unconvinced. After a 12-hour detention during which they said they were interrogated in all seriousness about their mission in America by humorless officers, including questions about another tweet referring to "digging up Marilyn Monroe," they were put on a plane back to England. The episode, which indicates that the US security establishment is now monitoring social networking sites such as Twitter and Facebook in its effort to safeguard American interests, has raised questions about how well security folks understand social media and its patois, and at what point innocuous banter is regarded as a national security threat. There are also concerns about whether overzealous security mandarins are wasting resources by chasing online phantoms. In one controversial case relating to India, Vikram Buddhi, an Indian doctoral student from Purdue University, has been in prison for more than five years after he allegedly posted messages on the Internet calling on the people of Iraq to resist the American invasion and urging them to kill then President Bush and his vice-president Dick Cheney. While some have argued that the Buddhi case relates to overzealous prosecution of an online caper, the latest incident, one report said, "appeared to demonstrate a less-than-full understanding of social media by agents." The offending tweet by Irishman Leigh Van Bryan, posted on January 16, read: "@MelissaxWalton free this week for a quick gossip/prep before I go and destroy America?" Instructive from the flap is a warning to social media schmoozers to refrain from casual talk about security issues. US security agencies have made no secret of the fact that they are developing plans -- and apps -- to scour the Internet for any potential threat to national security. Plans include trolling social networking sites such as Twitter, Facebook, and MySpace, looking for profiles and patterns that add up to threats. US deports two European tourists over 'destroy America' tweet - The Times of India --- This is called real-time internet monitoring !