India is exploring options to further strengthen its air defense by acquiring additional Russian-made S-400 Triumf surface-to-air missile systems or upgrading to the next-generation S-500 Prometei launchers, defense sources said, News.Az reports, citing The Print. That deal, covering five S-400 systems, included a follow-on clause allowing India to procure five more at the same terms—subject to adjustments for inflation and dollar value changes. The discussions signal New Delhi’s intent to expand its long-range missile defense shield as regional security dynamics evolve. Sources further said that the need for more S-400 or S-500 systems is part of the list of capabilities drawn up by the Defence Secretary prior to Operation Sindoor itself. “The S-400 performed very well in Operation Sindoor, and has a huge deterrence and punitive capability.