Stage: Fortress of the Soviet Union
The Zveno-9 is the first boss encountered in the Soviet Union stage. It is a large bomber airplane which attacks the player with fireballs and which carries smaller bombers under its wings. Zveno-9 is followed by two other bosses: Novgorod and Maxim Gorky.
Zveno-9 is based off the Soviet Union's Zveno Project. The Zveno configuration consisted of a large plane (the "parent" bomber) which served as a mother ship to smaller planes (the "child" bombers). While several combinations of parent and child bombers existed, there was no real-life Zveno-9, only Zveno-1 through -7 (excepting Zveno-4).