Iran cut off access to most virtual private networks (VPNs) in what appears to be a final step toward implementing its “halal” intranet, an entirely domestic version of the internet controlled by the government.

VPNs are used by many Iranians to route around censorship of websites like Facebook, YouTube, and many international news outlets. “Within the last few days, illegal VPN ports in the country have been blocked,” Ramezanali Sobhani-Fard, head of the Iranian parliament’s information and technology committee, told state media, according to a Reuters translation. “Only legal and registered VPNs can from now on be used.”

It’s not entirely clear why Iran moved to cut off the loophole now, but the timing is suggestive. Government officials had previously said the domestic intranet would be ready by this month, which could mean the VPN ban is a precursor to a wider rollout of the new system. And the presidential election, Iran’s first since widespread protests broke out in 2009, is coming up in June.

Read more at Quartz.