The State Security Department or VSD (Lithuanian: Valstybės saugumo departamentas) is a Lithuanian intelligence agency which collects information on threats to national security and works to eliminate those threats.

The VSD also conducts counterintelligence, protects state secrets and classified information, and vets certain applicants for residence permits or entry to Lithuania.

The origins of the institution are in the Intelligence Unit established within the Lithuanian Armed Forces on 27 October 1918.

[2] At that time, the department was also responsible for certain aspects of law enforcement: providing protection to state officials and strategic objects, ensuring integrity of state communications network, investigating political corruption.

Other agencies took over these extra duties and, during 2010, the mission of VSD was clarified to mainly focus on intelligence and counterintelligence.