Old IRBM silos

"The original S-2 strategic missile force formed the main land-based element of the French force de frappe, (later the force de dissuasion) from the early 1970s. In 1973 a program was initiated to develop the second generation SSBS Sol-Sol-Balistique-Stratégique) system, the S-3, entailing the renovation of the first two groups of S-2 silos and replacing the missiles with the S-3 model. Development of the S-3 was completed in 1980. Deployment of the S-3 began in 1980, and both groups of nine silos were operational by the end of 1982."