NEW DELHI: Defence Minister Rajnath Singh launched the fourth nuclear-powered ballistic missile submarine, which will be the navy's strength in maritime security. The ceremony was held secretly on the 16th in Visakhapatnam. The K-4 nuclear ballistic missiles are capable of hitting targets at a distance of 3,500 km. Codenamed S4, the submarine will undergo various tests in the coming days.

S-4 is a modified version of the S-3 or INS Arighaat, commissioned in August. The K-15 missiles in Arighaat have a range of 750 km. The recently commissioned S2 or INS Arihant and INS Arighaat are on deep-sea patrol.

S4 defence: It aims to counter China's long-range missiles such as Dongfeng-21 and Dongfeng-26 and enhance defence in the Indo-Pacific region.

India's nuclear submarine series:

S.1: INS Chakra

S2: INS Arihant

S3: INS Arighaat

S4: INS Aridhaman (official name to be announced later)

In the next stage, a submarine carrying nuclear missiles with a strike range of more than 7000 km