India Announces Major Missile Test, Establishes 3,550 km No-Fly Zone in Bay of Bengal
India has announced a significant missile test in the Bay of Bengal, scheduled between December 17 and 20, 2025, as indicated by a Notice to Airmen (NOTAM). This test marks a substantial advancement in India's strategic missile capabilities. The NOTAM outlines an extensive no-fly and no-ship exclusion zone extending up to 3,550 km, making it one of the largest safety corridors ever declared for an Indian missile test.
According to defense sources, the NOTAM will be effective daily from 6:00 am to 6:00 pm IST during the testing period. Civilian aviation and maritime operations have been advised to alter their routes. The Indian Air Force and Indian Navy will collaborate to enforce the restricted zone, ensuring safety due to potential debris from missile stages.
The size of the exclusion zone surpasses the 1,480 km safety area previously announced during an October 2025 missile test, suggesting the evaluation of a longer-range strategic system.
Likely Test of K-4 Submarine-Launched Ballistic Missile
Defense analysts believe the test is likely for the K-4 submarine-launched ballistic missile (SLBM), a critical element of India's sea-based nuclear deterrent. Developed by the Defence Research and Development Organisation (DRDO), the K-4, powered by solid fuel, is an evolution of the Agni-series missile technology and addresses the limitations of the shorter-range K-15 Sagarika.
The K-4 program was initiated following the launch of INS Arihant in 2009 to ensure India has a credible and survivable second-strike capability under its doctrine of credible minimum deterrence.
Submarine Integration and Operational Status
INS Arihant, commissioned in 2016, and INS Arighat, commissioned in 2024, are equipped to carry four K-4 missiles each. Future submarines S4 and S4* are expected to carry up to eight missiles each. By mid-2025, the K-4 reportedly reached full operational status on Arihant-class SSBNs, with deterrent patrols conducted following user trials on INS Arighat.
The test from December 17 to 20 aims to further validate the missile’s range, accuracy, and system integration, possibly as part of advanced user or operational trials.
Strategic Significance
With an operational range of 3,000–3,500 km, the K-4 allows India to target strategic locations while remaining secure in ocean bastions, thereby enhancing the sea component of its nuclear triad. It represents a significant improvement over the 750 km-range K-15 and paves the way for future systems like the K-5 (5,000+ km) and the MIRV-capable K-6 (8,000 km), which are planned for the next-generation S5-class SSBNs in the 2030s.
The missile’s development is part of India’s broader maritime and strategic expansion on the eastern seaboard, centered around Visakhapatnam, which hosts crucial nuclear submarine and missile infrastructure.
Why the 2,520 km Exclusion Zone Matters
The enlarged safety corridor highlights the complexity of testing full-range ballistic missiles, covering the boost-phase ascent, mid-course flight, and terminal re-entry phases. The need for solid-fuel stage separation, potential MIRV testing, and splashdown zones requires broader safety buffers.
Defense sources mention that previous K-4 trials in late 2024 involved exclusion zones of about 2,000 km, with the current expansion indicating growing confidence and maturity of the system as it nears sustained deployment.
If successful, this test will reinforce India’s position among a select group of nations possessing credible sea-based nuclear deterrence, thus enhancing strategic stability in the Indo-Pacific amid evolving regional security dynamics.
