The fourth squadron of the S-400 Sudarshan long-range surface-to-air missile system has recently arrived in India, enhancing the country's air defence capabilities. This delivery is part of a larger procurement agreement made in 2018, where India committed to acquiring five S-400 squadrons from Russia. The first three squadrons were delivered approximately two years ago, while the remaining two faced delays due to the ongoing Russia-Ukraine conflict. Notably, the S-400 system demonstrated its effectiveness during Operation Sindoor in May 2025, where it successfully engaged and downed a high-value Pakistani surveillance aircraft from a distance exceeding 300 km. The final squadron under the initial contract is expected to arrive within the next few months. In a strategic move to further bolster its air defence, the Defence Acquisition Council has also approved the procurement of five additional S-400 squadrons. Concurrently, India is advancing Project Kusha, an indigenous initiative aimed at developing a long-range air defence system capable of countering various aerial threats, including drones, with Solar Industries as a key development partner.