50 USC 1526 - Effective use of resources for nonproliferation programs

(a) Prohibition 
Except as provided in subsection (b) of this section, no assistance may be provided by the United States Government to any person who is involved in the research, development, design, testing, or evaluation of chemical or biological weapons for offensive purposes.
(b) Exception 
The prohibition contained in subsection (a) of this section shall not apply to any activity conducted pursuant to title V of the National Security Act of 1947 (50 U.S.C. 413 et seq.).