The Indian Army has published a request for information (RFI) for a prospective new short range surface-to-air missile system to replace its Soviet-vintage OSA-AK (SA-8) and SA-6 units, long overdue for overhaul and replacement. The Army is looking for a 20-km range missile system with active and passive guidance, with the capacity to engage targets moving upto 500 metres/second, and including hovering targets. In the RFI, the Army wants to know if prospective bidders' systems can be (a) mounted on wheeled chassis, (b) capable of being rail transported in India, (c) operated in desert, semi-desert and Indian plain conditions.