NEW DELHI: Russia may remain India's biggest defence supplier for the next two decades but its tardy supply of spares and after-sales service is forcing New Delhi to increasingly tap other countries to maintain Russian-origin aircraft, helicopters and other weapon systems.Over the last couple of months, IAF has floated a slew of global tenders for spares and special tools for MiG-23 and MiG-29 fighters, IL-76 and AN-32 transport aircraft, Mi-17 helicopters and OSA-AK surface-to-air missile systems.Now, the Army too has jumped on to the bandwagon for different equipment, which includes a global RFI (request for information) for acquiring "active protection and counter-measure systems" for its T-90S main-battle tanks, which have faced several technical problems since their induction began over the last decade."Yes, the international market is being explored to get spares for our Russian-origin equipment. We will still go to the Russian OEMs (original equipment manufacturer) for specialized spares. But we can get generalized spares at much cheaper rates from elsewhere," said a senior officer.This comes after years of India trying to get Russia to ensure uninterrupted supply of spares and regular maintenance, with even defence minister A K Antony regularly raising it with his Russian counterpart."In some cases, Russia has resolved the issue. But in many others, problems with breakdown and service maintenance spares continue... some acute, some manageable," said another officer.India has had an expansive defence partnership with Russia, with the latter notching up military sales well over $35 billion since the 1960s, leading to over 60% of equipment held by Indian armed forces being of Russian-origin.Ongoing bilateral defence projects are worth another $15 billion. IAF is progressively inducting 272 Sukhoi-30MKIs at a cost of around $12 billion from Russia. The figures will further zoom north with India slated to spend $35 billion over the next two decades to induct 250 to 300 of the stealth fifth-generation fighter aircraft ( FGFA ) from 2020 onwards.