H-1 upgrade program
The H-1 upgrade program is the United States Marine Corps's program to develop the AH-1Z Viper and UH-1Y Venom military helicopters to replace its aging fleets of AH-1W SuperCobras and UH-1N Twin Hueys . 
<triplet> AH-1Z Viper <subj> United States Marine Corps <obj> operator <triplet> UH-1Y Venom <subj> United States Marine Corps <obj> operator <triplet> AH-1W SuperCobra <subj> United States Marine Corps <obj> operator