Rainmaking Is Used As Weapon by U.S.
US civilian and mil sources, in series of ints, say USAF and CIA have been secretly seeding clouds over N and S Vietnam and Laos to increase and control rainfall for mil purposes; seeding program aimed most recently at hindering movement of N Vietnamese troops and supplies and suppressing enemy AA fire; disclosure confirms growing speculation in Cong and scientific circles about use of weather modification in SE Asia; program, 1st tried in S Vietnam in '63, is 1st confirmed use of meteorological warfare and has been opposed by some US State Dept officials; it is not determined if operations are in current use; many mil and US Govt officials doubt effectiveness of operations; details on operations