INS Chakra is sailing to Vladivostok, Russia where she will be returned from where she was leased

New Delhi: The unexpected emergence of the Indian Navy's only nuclear powered attack submarine, the INS Chakra, in the waters of the Singapore Straits heralds the end of her service in the Indian Navy.

NDTV has learned that the 8,140-ton submarine is presently en route to Vladivostok, Russia where she is being returned approximately ten months prior to the expiry of her ten-year lease that cost New Delhi approximately $2 billion. She is being operated by an Indian crew and is being accompanied by a Russian and Indian warship.

A submarine of the Russian Akula-2 Class, Chakra was commissioned into the Indian Navy on April 4, 2012 and was based in Visakhapatnam. She was the second nuclear-powered submarine acquired by India from Russia bearing the name Chakra.

Sources tell NDTV that the early return of the submarine became necessary because of her ''increasingly unreliable powerplant and maintenance issues'' besides the overall condition of the vessel which was extensively used by the Indian Navy to train crews on advanced nuclear submarines. This was a critical learning experience that paved the way for Navy officers to graduate to the made-in-India ballistic missile submarines, INS Arihant and INS Arighat, which presently form India's submarine-based nuclear deterrent.

NDTV has learned that over the last decade, the Indian Navy has, on occasion, deployed the Chakra in missions to track the movement of Chinese warships and possibly submarines in the Indian Navy. The growing expansion of the Chinese Navy and its deployment in the waters of the Indian Ocean and to its base in Djibouti in the Horn of Africa remains the primary concern for the Indian Navy. China has, by far, the fastest growing Navy in the world equipped with new generation nuclear submarines, cruisers and destroyers among a host of state-of-the-art warships.

INS Chakra will eventually be replaced by a more advanced variant of the same class of submarine which will also be known by the name Chakra. A $3 billion deal was signed in March 2019 for a ten-year lease for the new submarine, the delivery of which is expected by 2025. This will leave the Indian Navy without a nuclear-powered attack submarine for approximately four years.