S.D.I.

SDI (no periods) or S.D.I.,

1. Selective Dissemination of Information (a computerized system for data on published technical literature).

2. Strategic Defense Initiative (a system of computer-controlled defense using lasers and nuclear ballistic missiles in space to intercept and destroy enemy missiles before they reach their targets): »

Opponents point out that even if both nations had an SDI, the situation would be unstable because of the temptation for one nation to strike first (R. M. Lawrence).