Context: India's second nuclear-powered ballistic missile submarine, INS Arighat, was commissioned into the Navy on Thursday at Visakhapatnam in Andhra Pradesh. 

• With this, India continues to strengthen its nuclear triad, enhancing its ability to maintain a credible second-strike capability. 

• The addition of INS Arighat, the second SSBN (Ship, Submersible, Ballistic, Nuclear), marks an important milestone in India's nuclear submarine program.

Background

• India's first SSBN, INS Arihant, was commissioned in 2016. Both submarines are part of a four-SSBN project, with two more, currently known as S4 and S4*, still under construction.

About INS Arighat 

• It is expected to be armed with K-15 ballistic missiles, which have a range of 750 kilometers, adding significant strength to the Indian Navy's arsenal. 

• The submarine has been under construction and testing since its launch in 2017 at the Ship Building Centre (SBC) in Visakhapatnam.

• The submarine, an upgraded version of INS Arihant, represents a major step forward in India's naval capabilities and strategic nuclear deterrence.

Key Features

• INS Arighat can reach a speed of 12–15 knots (22–28 km/h) on the surface and up to 24 knots (44 km/h) when submerged. 

• It features four missile launch tubes and can carry up to four K-4 Submarine Launched Ballistic Missiles (SLBMs) with a range exceeding 3,500 kilometers or twelve K-15 SLBMs with a range of about 750 kilometers.

• The K-15 missile can be fitted with a strategic nuclear warhead, and in addition to these missile systems, INS Arighat will also be armed with torpedoes.