Russia offered India 8-10 Su-57 fifth-generation fighters plus the longer-range R-77M air-to-air missile, but no decision has been made.
The IAF runs about 30 squadrons against an ideal 40, with Tejas Mark 1A deliveries delayed by US GE-404 engines.
Buying Russian jets raises maintenance and geopolitical concerns, given US pressure on India over Russian oil purchases.
