Popular microblogging service Twitter says it now has the ability to censor messages on a country-by-country basis to account for different laws around the world.

The U.S.-based company announced on its blog this week that it has not yet used the system, but that if it does, a notice will appear to the user saying the Twitter post — known as a “tweet” — has been removed in order to comply with the law of the country in which the user is operating.

Up to now any content Twitter deleted would be erased worldwide. Twitter says this way, a tweet restricted in a specific country will still be available to the rest of the world.

The approach is in stark contrast to a statement Twitter made a year ago called “The Tweets Must Flow,” promising not to censor Twitter messages as they helped foment anti-government movements in a number of Middle Eastern countries.

In its latest announcement, Twitter said as it grows internationally, it is entering countries that have different ideas about the limits of freedom of expression. It said the laws are such that it cannot exist in some countries at all, while other nations are similar to the U.S. but restrict certain topics. It gave the examples of France and Germany, where pro-Nazi speech is banned.

While Twitter did not list other nations specifically, another example could be Thailand, where it is illegal to speak ill of the monarchy. Twitter does not operate in some countries that strictly control media content, such as China.

The company's announcement immediately prompted concerns. Some users said they would take part Saturday in what they called a Twitter Blackout, vowing not to tweet for the day.