The development, proliferation, and use of weapons (and materials) mass destruction (WMD) – chemical, biological and nuclear weapons – remain a threat to European security. Attacks involving the deployment of chemical, biological, radioactive, and nuclear (CBRN) materials or agents can be hard to detect and attribute which makes the prevention and response to such attacks particularly challenging. Long before its invasion of Ukraine, Russia has perfected a wide-ranging arsenal of hybrid warfare tools deployed in Europe. Southeast Europe and Bulgaria in particular, remain vulnerable to the Kremlin’s influence operations and media capture strategies that are instrumental for the spread of disinformation and propaganda. This report outlines the existing policy, regulatory, and institutional arrangements for countering WMD hybrid threats in Bulgaria. It examines the national regulatory and policy instruments, competent authorities, and mechanisms involved in the (1) prevention of and response to suspicious CBRN events, (2) cybersecurity, and (3) countering disinformation.