Reports on the results of a recent study of the U.S.-Japanese special export control regime for high-performance computers. This briefing reviews the history and purpose of this regime and establishes a framework for analysis. This framework can be used to test the basic premises on which the control regime rests and to suggest viable control thresholds. The briefing reviews the necessity of high-performance computers in U.S. government national security applications. It suggests the levels of export control that are possible for such systems, and discusses the desirability and feasibility of maintaining such controls. It also identifies the near- and intermediate-term problems that may erode the viability of the basic premises underlying high-performance computer export controls.