It is uncertain which missile DRDO is slated to test, it could well be the K-15 or the intermediate-range K-4. Here is a look at the K-15 "Sagarika"

The INS Arihant is India’s lone nuclear submarine which is equipped with the Pakistan specific Sagarika (Oceanic) Submarine Launched Strategic Missile (SLBM), also known by the code names K-15 or B-05, having a range of 750 km. A “strategic missile” is military euphemism for nuclear warhead-carrying missile capability. Indian scientists have been developing longer range SLBMs which will provide the country with a much-needed capability to take down long-range targets from underwater, the intermediate-range variant is called the K-4 which is also a nuclear capable submarine-launched ballistic missile with a maximum range of about 3,500 km. The K-4 will also arm the INS Arihant. The K-4 is purportedly a China specific deterrent system.

India has joined the league of select countries that have fully operational submarine-launched strategic missile systems capable of hitting targets with nuclear warheads at a range of 750 kilometres. Before this, such technologies were available only in the US, Russia, China and France.

A formal announcement of this achievement was made by Defence Minister Nirmala Sitharaman, who felicitated A Joseph and M Ugender Reddy, the two scientists who developed the missiles, during the annual award ceremony of the Defence Research Development Organisation in New Delhi in May 2018.
India’s costliest defence project — a Rs 90,000 crore push to develop and construct a fleet of nuclear-powered and nuclear-armed submarines monitored directly by National Security Adviser Ajit Doval — has been making steady progress away from media glare.

As per Missile Defence Advocacy website [Edited to current status], the Sagarika (K-15, B05) missile is a 650 to 750 km ranged Submarine Launched Ballistic Missile (SLBM). It is reportedly based on the Prithvi design. The program started in 1992 and was originally part of a program that would adapt a ramjet engine to Indian missiles. The missile was developed by the DRDO complex in Hyderabad. In 2007, India tested the Sagarika from a submersible pontoon launcher. It was tested again in February of 2008 from another pontoon, simulating the environment of a submarine. Its final trial was on January 27, 2013 as it successful hit a predetermined target from an underwater battery. It typically carries warhead of around 1,000 kg, and uses solid fuel. It is deployed with the Indian Navy’s new ballistic missile submarine INS Arihant.


Designation Sagarika / K-15  / B05
Missile Variants Prtihvi / Shaurya
Mobility and Role Sub-Launched/Short-Range Ballistic Missile
Operator Indian Navy
Range 750 km
Warhead Type / Weight Nuclear or Conventional / 1,000 kg
MIRV and Yield No MIRV Capabilities
Guidance System/Accuracy Inertial Navigation / 40m CEP
Stages / Propellant 2 Stages / 1 Underwater Booster-Solid Fuel Motor
IOC / Status 2014 / In service
Status / Number of Units Operational / N/A
Data Courtesy: Missile Defence Advocacy, The Hindu , India Today        

The effort has borne fruit in recent years in the form of INS Arihant – India’s first indigenously built SSBN – a submarine that is powered by a nuclear reactor and is equipped with nuclear-tipped ballistic missiles. Following an unfortunate accident due to human error, a highly placed source told media that the INS Arihant SSBN has been repaired and made available to the Indian Navy as the damage was not substantial, contrary to initial fears. The second Arihant class submarine, INS Arighat, was launched by Defence Minister Nirmala Sitharaman during a low profile ceremony at the Ship Building Centre (SBC) dry-dock in Visakhapatnam on 19 November 2017, a report by Sandeep Unnithan of India Today had revealed.

Two other SSBNs, which are still unnamed, will be launched by 2020 and 2022. The two boats will displace 1,000 tonnes more than the Arihant class and will be equipped with eight ballistic missiles or twice the Arihant's missile load.

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