▁range ▁of ▁a ▁sil o , ▁and ▁then ▁shoot ▁just ▁those ▁ones . ▁This ▁meant ▁a ▁small ▁number ▁of ▁AB M s ▁would ▁be ▁effective ▁against ▁a ▁huge ▁number ▁of ▁Soviet ▁war head s . ▁ ▁AR PA ▁began ▁research ing ▁such ▁a ▁system ▁under ▁the ▁name ▁Hard point . ▁To ▁ensure ▁they ▁shot ▁only ▁at ▁valid ▁targets , ▁it ▁had ▁to ▁generate ▁very ▁accurate ▁tracks ▁for ▁the ▁enemy ▁war head s . ▁They ▁also ▁had ▁only ▁seconds ▁to ▁develop ▁that ▁track ▁and ▁launch ▁a ▁miss ile , ▁assuming ▁that ▁that ▁air ▁would ▁be ▁filled ▁with ▁nuclear ▁explos ions ▁that ▁would ▁render ▁higher ▁alt itudes ▁op aque ▁to ▁rad ar , ▁an ▁effect ▁known ▁as ▁nuclear ▁black out . ▁They ▁began ▁development ▁of ▁a ▁new ▁rad ar ▁known ▁as ▁the ▁Hard point ▁Dem on str ation ▁Array ▁Rad ar , ▁or ▁H AP D AR , ▁and ▁a ▁new ▁extremely ▁high - speed ▁miss ile ▁known ▁as ▁H IB EX . ▁The ▁entire ▁eng agement ▁would ▁last ▁just ▁over ▁two ▁seconds , ▁with ▁the ▁intercept ▁taking ▁place ▁at ▁about ▁ ▁alt itude . ▁They ▁later ▁added ▁a ▁second ▁stage ▁to ▁H IB EX ▁known ▁as ▁UP ST AGE , ▁demonstr ating ▁over ▁ 3 0 0 ▁g ▁of ▁later al ▁acceleration , ▁allowing ▁it ▁to ▁counter ▁man eu ver ing ▁war head s . ▁ ▁AR PA ▁released ▁its ▁Hard point ▁study ▁in ▁ 1 9 6 5 . ▁It ▁presented ▁a ▁way ▁for ▁the ▁Army ▁to ▁offer ▁an ▁effective ▁AB M ▁system