In the past 2 years. more than a third of the 50 proposals offered under one part of the IREX program had to be rejected or modified in order to minimize the technology loss. An even more common technology drain is that found through scientific visits to academic conferences and attendance at commercial trade fairs. Soviets need only a visa approved by the State Department to enter the United States for this purpose. A Soviet scientist. for example. was able to study fuelair explosives in this country and to return to the Soviet Union to work on related weapons development. The vast majority of militarily significant technology obtained by the Soviet Union is acquired through intelligence agencies of the Soviets and other Eastern European countries.