Facebook’s local servers in Vietnam were taken offline early this year, slowing local traffic to a crawl until it agreed to significantly increase the censorship of “anti-state” posts for local users, two sources at the company said Tuesday.

The restrictions, which the sources said were carried out by state-owned telecommunications companies, knocked the servers offline for around seven weeks, meaning the website became unusable at times.

“We believe the action was taken to place significant pressure on us to increase our compliance with legal takedown orders when it comes to content that our users in Vietnam see,” the first of the two Facebook sources said.

In an emailed statement, Facebook confirmed it had reluctantly complied with the government’s request to “restrict access to content which it has deemed to be illegal.”

Vietnam’s foreign ministry, which handles requests from foreign journalists for comment from the government, did not respond to a Reuters request. State telecoms firms Viettel and Vietnam Posts and Telecommunications Group (VNPT) also did not respond to requests for comment.

Commenting on the Reuters report, human rights group Amnesty International called on Facebook to immediately reverse its decision.

“Facebook’s compliance with these demands sets a dangerous precedent. Governments around the world will see this as an open invitation to enlist Facebook in the service of state censorship,” the group said in a statement on Wednesday.

Facebook has faced pressure to take down anti-government content in many countries over the years.

In Vietnam, despite sweeping economic reform and increasing openness to social change, the ruling Communist Party retains tight control of media and tolerates little dissent, ranking 175th of 180 countries on Reporters Without Borders’ World Press Freedom Index.

To that end, it keeps a close watch on Facebook, which serves over 65 million users as the main platform for both e-commerce and expressions of political dissent.

Early last year, Vietnam accused Facebook of violating a new cybersecurity law by allowing users to post anti-government comments on the platform.

In the months that followed, Amnesty International said at least 16 people were arrested, detained or convicted for such posts. In November, state media reported that five more had been jailed.

The cybersecurity law requires foreign companies such as Facebook to set up local offices and store data in Vietnam — although Facebook says it does not store user data in the country.

The Facebook sources said the company typically resists requests to block access to user posts in a specific country, but the pressure of having its local servers impeded had forced it to comply.

“To be clear, that does not mean we will be complying with every request that the government sends us. But we did commit to restricting significantly more content,” one source said.

Facebook’s statement said: “We believe freedom of expression is a fundamental human right, and work hard to protect and defend this important civil liberty around the world. … However, we have taken this action to ensure our services remain available and usable for millions of people in Vietnam, who rely on them every day.”

Since 2016, Vietnam has become of one of Facebook’s biggest markets in Asia.

According to Ants, a Vietnam-based market researcher, digital advertising revenue in Vietnam amounted to around $550 million in 2018, 70 percent of which went to U.S. social media giants Facebook and Google.

The server shutdown began in mid-February and persisted until early April, the sources said, at the same time as concerns about the spread of the novel coronavirus were intensifying.

With Facebook usage so widespread in Vietnam, users began to notice that access was slow to Facebook as well as its Messenger chatting app and its picture-blogging site, Instagram.

State media at the time blamed the slowdown on maintenance to undersea cables, and state telecoms firms apologized for unstable access to Facebook.

“VNPT and partners are actively working to check and rectify the problem,” VNPT said in a statement at the time.

But behind the scenes, as Facebook struggled to maintain its services, it was talking to the government, the sources said.

“Once we committed to restricting more content, then after that, the servers were turned back online by the telecommunications operators,” one source said.

The second source contrasted the drop in traffic in Vietnam with a surge elsewhere as dozens of countries put in place restrictions on movement that encouraged separated friends and families to turn to Facebook.

“Vietnamese telcos were unique in restricting access at a time when people need services like Facebook. It was a sharp contrast with other places in the world,” they said. “Thankfully, that’s now resolved.”