Vietnamese online users are banned from talking about current affairs from now on.
A new law, dubbed decree 72, says blogs and social websites should not be used to share news articles, but only personal information. Foreign internet companies will have to keep their local servers inside Vietnam.
The move has been slammed by everyone under the sun from internet companies and human rights groups, as well as the US government. However Vietnam is a one-party communist state and the authorities maintain a tight grip on the media. So far shedloads of activists, and bloggers, have been convicted for anti-state activity in the country this year.
The new law specifies that social networking sites such as Twitter and Facebook should only be used "to provide and exchange personal information".
Reporters Without Borders, a Paris-based group that campaigns for press freedom worldwide, has said the decree will leave Vietnamese people "permanently deprived of the independent and outspoken information that normally circulates in blogs and forums".