Military Counterintelligence Day is observed in Ukraine every December 18 to honor the Military Counterintelligence Department of the Security Service of Ukraine (SBU). This observance was established to recognize the contributions of military counterintelligence to national security, particularly in times of war. The day commemorates the signing of the Decree “On Counterintelligence Support of Military Formations” by President Leonid Kravchuk in 1991, which laid the groundwork for the department's responsibilities, including protecting the Armed Forces and preventing foreign intelligence infiltration. The SBU has undergone several reorganizations since its inception, with significant changes occurring after 2014 due to the annexation of Crimea and the onset of the War in Donbas. Military Counterintelligence Day serves to highlight the often-classified achievements of those working in this critical area, emphasizing their role in safeguarding Ukraine's defense capabilities.