Kilo class submarine project 636 3D model

The Kilo-class submarines are a group of diesel-electric attack submarines designed by the Rubin Design Bureau in the Soviet Union in the 1970s and built originally for the Soviet Navy.

The first version had the Soviet designation Project 877 Paltus , NATO reporting name Kilo. They entered operational service in 1980 and continued being built until the mid-1990s, when production switched to the more advanced Project 636 Varshavyanka variant, also known in the West as the Improved Kilo class. The design was updated again by the Russian Navy in the mid-2010s, to a variant called Project 636.3, also known as Improved Kilo II.