FOST is the main element of the strategic nuclear force. Providing a capability at any time of launching a retaliatory second strike, the SSBN provides a deterrent against any aggressor against the vital French interests. The order of engagement would be given directly by the President of the Republic. At sea, the SSBN is an entirely autonomous strategic base, which remains hidden throughout its patrol. Each submarine is fitted with 16 missiles, each equipped with six nuclear warheads. FOST therefore holds the majority of the French nuclear weapons.
The commissioning in 1997 of Le Triomphant new generation SSBN, followed by Le Téméraire in 1999, materialised the renewal and the future of FOST. Endowed with enhanced acoustic stealth performance, these submarines are armed with M-45 missiles, equipped with TN-75 nuclear warheads. From 2008, a new missile, the M-51 will be introduced, which will provide much improved performance compared with the M-45. FOST also has an operational base intended for the reconditioning of the SSBNs and crew, command centres and specific transmission stations.