The Vietnamese government restricted, and sometimes outright blocked, access to Facebook in the country from Sunday to Wednesday of this week during President Obama's visit, say two activists groups that spoke with Reuters. The move was designed to prevent critics of the communist-run government from organizing protests using the social network.

News of the Facebook blackout made its way out of the country via Twitter and through reports to help lines operated by Access Now, a digital advocacy group. Access Now works with Viet Tan, a pro-democracy activist organization operating in the country, to promote human rights and free expression. Obama's visit was intended to help bolster relations between the US and Vietnam, yet he was denied the right to speak with critics of the government during his three-day stay.

Unfortunately, shutting off access to Facebook is not uncommon in Vietnam. "People were using Facebook to call for protests. They did not want people to take to the streets," Angelina Huynh, an advocacy director for Viet Tan, told Reuters in an interview. Wielding access to Facebook and Twitter as a weapon against activists is also a routine practice in other countries throughout Asia, Africa, and the Middle East, where political tensions run high and access to telecom tools is highly regulated and restricted by the government.