The U.S. State Department says it is “troubled” by Russia’s decision to ban two of liberal billionaire George Soros' pro-democracy charities and label the organizations a threat to national security.

“Today’s designation of the Open Society Foundations and the Open Society Institute Assistance Foundation as so-called ‘undesirable’ organizations will only further restrict the work of civil society in Russia for the benefit of the Russian people,” State Department spokesman Mark Toner said Monday. “This action is yet another example of the Russian Government’s growing crackdown on independent voices and a deliberate step to further isolate the Russian people from the world.”

A spokesperson from Russia’s Prosecutor General’s Office said the activities of the fund are threats to state security and the Russian constitution, Radio Free Europe reports.

The Open Society Foundations said in a statement on its website that it was “dismayed” by the decision.

“Contrary to the Russian prosecutor’s allegations, the Open Society Foundations have, for more than a quarter-century, helped to strengthen the rule of law in Russia and protect the rights of all,” the statement read.

Prosecutors started investigating the charity fund in July after Russian senators flagged a list of 12 groups that required a closer look over their supposed anti-Russian activities, RT reports.

Other groups on the list include the National Endowment for Democracy, the International Republican Institute, the MacArthur Foundation and Freedom House.

Once a group in Russia is recognized as “undesirable,” its assets in the country must be frozen, its offices closed and the distribution of any of its materials is outlawed, RT reports.

Violators of the ban could face heavy fines and jail time.