According to information published by the Asian News International on June 3, 2021, the Indian Navy is about to launch an international tender for six new advanced submarines

The Project 75I-class submarine is a follow-on of the Project 75 Kalvari-class submarine for the Indian Navy. Under this project, the Indian Navy intends to acquire six diesel-electric submarines, which will also feature advanced air-independent propulsion systems to enable them to stay submerged for a longer duration and substantially increase their operational range. All six submarines are expected to be constructed in Indian shipyards.

The Project 75I-class submarines will have a vertical launch system (VLS) to enable them to carry multiple Brahmos supersonic cruise missiles, making the submarines fully capable of anti-surface and anti-ship warfare missions. Project 75i submarines will also be armed with torpedoes and will feature advanced stealth capabilities such as a greater ability to suppress noise and acoustic signatures. Submarines will also be outfitted with Air-independent propulsion (AIP) fuel cells which can significantly increase submerged endurance and operational range.

The BrahMos (designated PJ-10) is a medium-range ramjet supersonic cruise missile that can be launched from submarines, ships, aircraft, or land. It is a joint venture between the Russian Federation's NPO Mashinostroyeniya and India's Defence Research and Development Organisation (DRDO), who together have formed BrahMos Aerospace. It is based on the Russian P-800 Oniks cruise missile and other similar sea-skimming Russian cruise missile technology.