India secretly launched the super destructive secret nuclear submarine S4

• India has launched its third Arihant-class a nuclear powered Submarine in Visakhapatnam.
• The low-key launch was reported by UK-based Janes Defence Weekly through satellite imagery from the Vishakhapatnam Ship Building Center.
• The first SSBN INS Arihant was commissioned in 2016, while the second, though initially launched in 2014, is awaiting commissioning into the Indian Navy.

Strategic Strike Nuclear Submarines (SSBNs)

• These submarines are different from conventional SSK submarines, which use a diesel-electric engine as their power source, and have to surface daily to get oxygen for fuel combustion.
• SSBNs are bigger in size and are powered by a nuclear reactor and as a result, they can function submerged for months without having to surface.
• This feature allows them to travel further and with greater stealth.
• SSBNs are supposed to be the best guarantor of a second-strike capability in a nuclear exchange.
• SSBNs like the INS Arihant are also different from the nuclear-powered attack submarines (SSN), as they can carry ballistic missiles with nuclear warheads.
• The construction, commissioning, testing and status of the SSBNs are directly under the Strategic Forces Command (SFC) or the Strategic Nuclear Command (SNC), which is under the control of the PMO (Prime Minister’s Office).
• To complete the nuclear triad (nuclear weapon operability from air, land and sea) India aims to have at least four SSBNs.

S-4 submarine

• It is learnt that S4 is bigger in size, tonnage and capability compared to S2 and S3.
• Sources say unlike S2 and S3, which can carry four K-4 or 12 K-15 SLBMs (submarine launched ballistic missiles), S4 is being built to accommodate eight K-4 or 24 K-15 SLBMs.
• The missiles can be launched through vertical tubes, when the submarines are in submerged state.