India is set to commission its third -- and most powerful -- nuclear-powered ballistic missile submarine, the INS Aridhaman (codename: S4). But this isn't just another ship joining the fleet, it marks a critical tipping point in India's national security architecture.

INS Aridhaman is the most complex and devastating weapon to exist in India's weapons arsenal.

In this episode of In Our Defence, host Dev Goswami and defence expert Sandeep Unnithan decode the secrecy shrouding the Advanced Technology Vessel (ATV) project. They explain the "Rule of Three" (why you need three subs to keep one at sea), the massive upgrade in firepower with the K-4 missiles, and how a memo during the 1960s kickstarted India's quest for nuclear-powered ballistic missile submarines.

Key discussion points:

The Upgrade: Why Aridhaman is bigger, deadlier, and carries double the missiles of INS Arihant.

The Range War: How the K-4 missile (3,500km) finally allows Indian subs to target threats without leaving the safety of home waters.

The History: PN Haksar memo and the birth of the Indian nuclear submarine program.

The Command: Who actually presses the red button? (Hint: It's not the Navy Chief).

Tune in for a deep dive into the "Silent Service" that protects India from the deep.

Produced by Taniya Dutta

Sound mixed by Aman Pal