There is little doubt that proliferation and the possibility of AUL warrant a serious response. Indeed, President Bush introduced GPALS as a prominent part of that response. It should be recalled, however, that in the past when SDI's immediate goal was to enhance deterrence, opponents of the program were quick to identify alternative measures to accomplish the same goal. Similarly, critics of GPALs already have identified their preferred alternatives for responding to the proliferation and accidental/unauthorized launch threats. A question that must be addressed, therefore, is whether there exist alternative countermeasures to these threats that would be effective and preferable to GPALS.