The U.S. federal government is banning Russian cybersecurity firm Kaspersky Labs from selling antivirus software in the United States, officials announced Thursday, citing significant national security risks.

Department of Commerce officials urged current Kaspersky customers to “immediately find alternatives” after an investigation determined that Russian state hackers could turn the cybersecurity software against their users. The full ban will officially take effect September 29 to allow current customers to replace their antivirus software products.