U.S. TikTok users hoping to find a workaround to access the banned app are finding that virtual private networks are no help, hinting that the company has taken extra precautions to ensure Americans are not able to avoid the ban.

Virtual private networks, more commonly known as VPNs, route internet traffic through servers located around the world. Using VPNs can help users sidestep government and corporate internet restrictions, though their security promises can sometimes be overstated.

Many on social media posted Saturday night into Sunday morning that their attempts to use VPNs to access TikTok were unsuccessful, and attempts made by NBC News were similarly thwarted.

It is not entirely clear how TikTok has instituted the ban at the technical level, but the failure of VPNs is notable because they proved effective when India banned TikTok.

Follow live coverage

The full range of how TikTok is identifying American users is not yet clear. The company didn’t immediately respond to a request for comment.

One explanation could be that TikTok is blocking all accounts registered with an American phone number as well as computers associated with those accounts.

NBC News tested a U.S. TikTok account with two VPNs Sunday morning and still received the same message sent to any U.S. user who tried to access the app since Saturday evening.

“Sorry, TikTok isn’t available right now. A law banning TikTok has been enacted in the U.S. Unfortunately, that means you can’t use TikTok for now. We are fortunate that President Trump has indicated that he will work with us on a solution to reinstate TikTok once he takes office. Please stay tuned!”

Despite their apparent ineffectiveness, multiple VPN apps were near the top of Apple’s App Store on Sunday.

NetBlocks, a company that tracks global internet censorship, said there was no indication that any internet service provider was blocking the app, and that its unavailability was purely through TikTok making the service inoperable for U.S. users.

In April, Biden signed a law that required TikTok to divest from its Chinese parent company, ByteDance, or risk being banned in the U.S. The law indicates that the ban would take the form of forcing the two primary app stores in the U.S., owned by Google and Apple, to no longer offer the app. Those stores currently do not have TikTok available.