Indiaâs Nuclear Submarine Programme To Reach Another Major Milestone With Commissioning Of Second SSBN, Arighat, Early Next Year by Swarajya Staff - Dec 18, 2020 12:42 PM Prime Minister Narendra Modi speaking at an event with an image of INS Arihant, its clearest pictures, in the background. (@narendramodi/Twitter) Snapshot The bigger, improved and better-armed INS Arighat is in the final stages of sea trials and is likely to be commissioned into service early next year. After teething troubles, including a crippling accident, Indiaâs nuclear submarine programme â the countryâs costliest defence project, monitored directly by National Security Adviser Ajit Doval â has made big strides in recent years.