The United States government is increasingly concerned about the Somali militant group Shabab's use of Twitter, and is considering options to have it shut down, according to the New York Times. Shabab has aligned itself with Al Qaeda, and it's been making prolific use of Twitter in recent weeks, using its @HSMPress account for everything from openly taunting the Kenyan army to boasting about the Somali telecom industry to criticizing the Times for reporting on... Shabab's use of Twitter. That's raised the attention of the US, which classified Shabab as a terrorist organization in 2008 and is worried about the group recruiting members in the West — administration officials believe they have the legal authority to demand Twitter shut down the group's account.
It's not clear exactly what legal mechanism the government plans to use to demand such a shutdown, but it's against the law to provide "material support or resources" to terrorist organizations, and the Supreme Court upheld a broad interpretation of that prohibition in 2010. For its part, Twitter has yet declined to comment, but it's hard to see the company putting up a big fight over the account of a terrorist group; we'll see how far this one goes.