Russian-built and NATO (USN, European) probe-and-drogue -- are they interoperable? Considering the current diversity of coalition air fleets in some parts of the world (the Horn of Africa situation comes to mind), can Russian-built tankers refuel NATO probe-and-drogue receivers, and vice versa? (Say, a US Navy F/A-18E getting a helping hand from an Indian Air Force Il-78MKI, or an Ethiopian Air Force Su-27 filling its tanks from a Royal Australian Air Force A330 MRTT?)
The drogue system was standardized in the 50s and reverse engineered by the USSR in that time so nearly all aircraft that use it are compatible with each other.