e 3° has been projected, varying in yields from a few hundred kilotons to about 1-1/2 megatons, and in altitudes from 20 kilometers to above 400 kilometer. However, practical considerations with respect to development of instrumentation techniques and related preparations make it unrealistic to plan for more than two of these shots in the short time available. Category two is that of advanced concepts for improving weapon effectiveness and decreasing warhead vulnerability, and these cover a wide range of possible design changes, etc. The third category noted includes tests that combine both developmental and weapons verification objectives. As to the designs that might be tested under this category the letter states "it is important that these designs be subject to experimental verification not nnly to give confidence as to the effectiveness of devices stockpiled as weapons but also, importantly to enable the laboratories to use the information so obtained as a basis for more advanced steps into new weapons technology. In addition to addressing the general categories and justification for the different types of tests which are desired for atmospheric conduct, the letter gives some specific justifications for the need for atmospheric testing including the problems inherent in solely underground testing, the great advances and the large data base that the Russians are building up in their accelerated atmospheric program, and specific military areas which can best be addressed only by atmospheric testing and are so very important to the nation's military defense strategy. In addition to noting the engineering problems with doing testing underground and the slowness with which such testing goes a strong point is made about the relative capability for diagnostic instrumentation with underground versus atmospheric testing. Further the question of an overseas test site is addressed and Eniwetok with its political difficulties versus the use of Christmas Island with the as yet wncertain availability are noted and it is stated that tests could be done by air drops probably staged from Hawaii with limited instrumentation on some small island such as Johnston which is at present being pursued but which is not as desirable as having a large island test base. Further it is stated that a special requirement exists in connection with the rocket lifted test shot for which Johnston Island is the most logical launch point because of the available facilities. He further addresses the question of outer space testing and states that because of the projected cost of an initial 100 million dollars over a two-year period to develop such a capability that such a capability is not being considered for the planned program. In the area of fallout and political implications of nuclear yield it is stated that a total yield of approximately 21 megaton of which abovt 8 megaton would be fission yield is projected for the planned series of events as compared to the approximately 120 megatens of yield already totaled during the recent Soviet tests. Part of the summary of the cover letter reads as follows: ''In addition to provisions for flexibility, current planning should provide for preparation for a second test series, about a year later, looking to more dramatic advances than are possible in an early time frame. In fact, it is essential to plan for a second series in order to accomplish the very important effects tests that could not be included in the early time scale. In looking at what test devices can be made available in the April to July period, it is apparent that we are suffering to some extent from the three-year test moratorium. During that period while the United States was negotiating in good faith, the bulk of our nuclear weapon design