Context

• India launched (October 16) its fourth nuclear-powered ballistic missile (SSBN) submarine at the Ship Building Centre (SBC) in Visakhapatnam in a bid to strengthen its nuclear deterrence against its adversaries.
• The launch took place after Defence Minister Rajnath Singh inaugurated the Very Low Frequency Naval Station in Damgundam forest area of ​​Vikarabad district in Telangana.

Nuclear-powered ballistic missile

• It is a nuclear-powered submarine capable of launching ballistic missiles from underwater. 
• First Ballistic Missile Submarine: INS Arihant
• India's first ballistic missile submarine INS Arihant was launched by the then Prime Minister Manmohan Singh and his wife Gursharan Kaur on July 26, 2009.
• With the construction of this 6000 tonne vessel, India became the sixth country to have such submarines.
• The other five countries are the US, Russia, China, Britain and France.
• After undergoing intensive port and sea trials, INS Arihant became part of the Navy fleet in 2016.
• INS Arihant can carry K-15 nuclear missiles with a range of 750 km.

Second submarine: INS Arighat

• The second submarine of the Arihant class, INS Arighat, has double the number of missiles, giving India the capability to carry more missiles in 'water warfare'.
• This submarine was codenamed S-3.
• Launch: After several postponements, its launch took place in 2017.
• This submarine was originally known as INS Aridaman but was named INS Arighat upon launch. 
• Third Nuclear Submarine: INS Aridaman
• The third nuclear submarine of the Arihant class, INS Arihant, was also launched from the Ship Building Center in Visakhapatnam on November 23, 2021, in which secrecy was also maintained.
• This nuclear submarine is 13.8 meters larger than INS Arihant.
• It can carry at least 8 K-4 ballistic missiles with it. India is planning to launch at least four such submarines into the sea to increase its maritime attack capability.
• INS Arihant will be inducted into the Navy next year.

 Features of SSBNs:

• Nuclear power: SSBN submarines are equipped with nuclear reactors, which gives them the ability to stay in the sea for a long time and complete the mission without surfacing.
• Ballistic missiles: These submarines carry ballistic missiles, which are capable of striking very far. These missiles can be fired from underwater and can target targets located thousands of kilometers away.
• Stealth: SSBN submarines can remain hidden inside the sea, due to which the enemy cannot easily find them. This makes them a powerful deterrent force.
• Destructive capability: The ballistic missiles installed in these submarines can be equipped with nuclear weapons, which can destroy a very large area