The U.S. government is changing visa procedures to make it easier for some foreign students wishing to study science or other technical fields in the United States.

　　The changes are intended to speed up the process of approving security clearances and allowing those clearances to remain in effect longer.

　　U.S. officials have struggled to balance competing goals of inviting foreign scholars, who provide an intellectual and financial boon to many American universities, while preventing sensitive technology from being illegally transferred out of the country.