The People's Republic of Bulgaria became a member of the Warsaw Pact in 1955. During the Cold War Bulgaria was a direct neighbor of NATO. NATO member Turkey and Greece were the southern neighbors.
During the Cold War Bulgaria received military technology from the Soviet Union cheaply or freely. In case of war, the Soviet Odessa Military District and Black Sea Fleet would support them.
The District became subordinate to the South-Western Strategic Direction in the early 80s.
The 1st, 2nd, and 3rd Bulgarian Armies were stationed in the country. The 10th Composite Air Corps supported these forces.