K-4 Missile Test: India Strengthens Sea-Based Nuclear Capability With 3,500-km Range

India has taken a major step in strengthening its strategic deterrence by successfully test-firing the K-4 intermediate-range ballistic missile from the nuclear-powered submarine INS Arighaat in the Bay of Bengal. The test, conducted off the coast of Visakhapatnam, underscores India’s growing capability to launch nuclear weapons from beneath the ocean’s surface—a critical component of its nuclear triad.

The K-4 submarine-launched ballistic missile (SLBM) boasts a range of approximately 3,500 kilometers, enabling India to target adversaries deep within their territory while remaining hidden in international waters.

This capability significantly enhances the survivability of India’s nuclear arsenal, ensuring a credible second-strike option in the event of a conflict.

Derived from the Agni-III land-based missile, the K-4 has been specially adapted for underwater deployment. It uses a cold-launch system to exit the submarine’s launch tube, rise through the water, and ignite its rocket motor upon reaching the surface.

The missile can carry a nuclear warhead weighing up to 2.5 tons, making it one of the most powerful weapons in India’s arsenal. It is designed for deployment on Arihant-class submarines, which operate silently on extended deterrence patrols, making them the stealthiest leg of India’s nuclear triad.

The successful test also highlights India’s technological progress in strategic weapons development. The K-series of missiles is named in honor of Dr. APJ Abdul Kalam, who spearheaded India’s Integrated Guided Missile Development Program (IGMDP).

With this achievement, India joins an elite group of nations—including the United States, Russia, China, France, and the UK—that possess the capability to launch nuclear weapons from land, air, and sea.

This milestone comes at a time of evolving security dynamics in the Indo-Pacific region, reinforcing India’s commitment to maintaining a credible and survivable nuclear deterrent. The operationalization of the K-4 missile marks a significant leap forward in India’s defense posture and strategic autonomy.