] ro hg he said, It is important, he pointed out, to learn the best: altitude at which to engage enemy ICBM's, Mr, Strauss et that it might be best to engage them at an altitude of 250,000 feet rather than lower since more fallout would remain in the curavosphere than from shots detonated at a lower altitude, General swoer pointed out that an anti-missile system aesigned to detonate at 250,000 feet would be much more costly than one designed to detonate at 125,000 feet, He also said in response to a commer’ by Mr, Strauss that there is not enough vime to develop for Operation HARDTACK a weapon system of lower vield which could be cetonated at these high altitudes, The Redstone rocket is being used, he said, because 1t is the only tested weapon at the present time which can be detonated at heig of 125,000 to 250,000 feet. General Loper observed that the DOD had no official knowl: edge of instructions from the President to limit off-site fallov to any specific amount, Strauss said, In several recent conversations, Mr, the President had not insisted upon a definite - limitation but had urged that it be> Kept to a minimun, Pag — ‘The. Commissioners briefly discussed ¢ with the ‘menberg the MLC the date for beginning ‘Operation HARDTACK, General Lor indicated that the DOD hoped to begin its five weapons effects tests on April 15, 1958, Mr, Strauss said that in view of the adjournment of the London disarmament discussions, the possibil of a test moratorium in 1958 was extrenely shtehe../Icess like! y./ - - Therefore, he said he believed there was now no’ urgency about beginning the tests early in 1958, and indicated’ ‘would not begin testing its devices prior to May 1. a é