India has taken delivery of its fourth Russian-made S-400 Sudarshan air defense squadron, completing most of a $5.43 billion deal from 2018 delayed by Russia's war in Ukraine. Each squadron packs radars, command posts, and launchers with up to 128 missiles, capable of tracking targets 600 km away and striking aircraft, drones, and missiles from 40 to 400 km. Proven in the 2025 Operation Sindoor conflict where it downed a Pakistani aircraft at over 300 km, the systems now protect fronts near Pakistan and China, with the fifth due by late 2026.
