The Defence Research and Development Organsiation (DRDO)  successfully test-fired the 3,500-km range submarine-launched ballistic missile, K-4, on 18 January 2020, from a submerged pontoon off the Visakhapatnam coast. The test met the desired parameters. A pontoon simulates the situation of a launch from a submarine.

What makes this test-firing of the K-4 missile more significant is the fact that a recent launch of the missile, conducted from a submerged platform in December 2017, had ended in a failure. The launch was not successful due to “a failure in the missile’s ignition following its ejection from the submerged pontoon.”

SLBMs are test-fired from submerged platforms not only to collect data to analyse its performance, but also to ensure safety. A failed launch from an active ballistic missile submarine would cause massive damage to its hull.

Developmental testing of the missile, which has an estimated maximum range of 3,500 kilometers and can be fitted with a 2,000-kilogram sub-kiloton nuclear or conventional payload, began in 2010.

The K-4 was last successfully test fired in full  operational configuration from India’s first domestically developed and built nuclear-powered ballistic missile submarine (SSBN), the INS Arihant, in April 2016. Notably, the K-4 has been tested using depressed trajectories.

The INS Arihant, the first-of-class of a planned fleet of four to five SSBNs based on the Russian Project 971 Akula I-class nuclear-powered attack submarine (SSN), has been designed to carry up to four K4s or 12 K-15 (B-05) short-range ballistic missiles (SLBM).

With the 3,500-km range K-4, INS Arihant and future SSBNs will be able to target parts of China, including Beijing, and all of Pakistan, from the northern parts of the Bay of Bengal. Not ideal, but better than the K-15.