France is upgrading the defenses on its ten nuclear subs (four SSBNs and six SSNs), by replacing the existing Dilsat countermeasures systems (against torpedoes) with the newer Nemesis. These countermeasures systems consist of software, libraries of sounds and decoys. When an oncoming torpedo is detected, the countermeasures system helps decide whether to use electronic deceptions (to confuse torpedoes with an active sonar) or decoys (mini-torpedoes that give off sound and/or electronic signals to guide the torpedo away from you.) Newer torpedoes have been equipped with better sensors, and the wire guided ones benefit from the better sensors found in the sub firing the torpedoes. Nemesis is not only designed to handle the most current torpedoes, but is easy to upgrade to deal with new torpedo developments.