Russia has submitted a proposal to supply five additional S-400 'Sudarshan' air defence units under a tender issued by India. The move is being seen as a step towards further strengthening India's existing air defence capabilities. India had earlier signed a contract with Russia in 2018 for the purchase of five S-400 squadrons. The S-400 is an advanced long-range surface-to-air missile system, also referred to in India as 'Sudarshan'. Detailed information regarding the tender process, cost, timeline, or any response from the Indian government on this new proposal is not currently available.