Complex sentence: The program leases a number of Antonov An-124 aircraft permanently for NATO missions which might occur, contracted from the Volga-Dnepr heavylift company and from Antonov Airlines.
Split into simpler sentences: The program leases a number of Antonov An-124 aircraft permanently for NATO missions which might occur. The aircraft are contracted from the Volga-Dnepr heavylift company and from Antonov Airlines.