India test fires 3,500-km K-4 missile from nuclear-powered submarine INS Arighaat on December 25, 2025

Key facts

• India tested an intermediate-range ballistic missile called K-4, which is designed to hit targets 3,500-km away, from the nuclear-powered submarine INS Arighaat in the Bay of Bengal on Tuesday.
• The solid-fuelled K-4 can carry a two-tonne nuclear payload and is critical for India to strengthen the sea leg of its nuclear weapons triad.
• INS Arighaat, the country's second nuclear-powered submarine with nuclear-tipped ballistic missiles (called SSBN in naval parlance), was commissioned on Aug 29 last year.
• India will commission its third SSBN as INS Aridhaman in the first quarter of 2026 and the fourth in 2027-28 under the secretive over Rs 90,000 crore ATV (advanced technology vessel) programme launched decades ago.
• The operational deployment of K-4 missiles, which will be followed by the K-5 and K-6 missiles in the 5,000 to 6,000-km range class, will somewhat help India narrow the huge gap with countries like the US, Russia and China.
• Her forerunner INS Arihant, which became fully operational in 2018, can carry only the 750-km range K-15 missiles.
• The SSBNs impart India's deterrence posture with much more credibility because they are considered the most secure, survivable and potent platforms for retaliatory strikes in line with the country's 'no first-use' policy.