(a) Notwithstanding any other provision of law, a fellowship, scholarship, or grant may, under regulations to be prescribed by the President or his designee, be made by a corporation, fund, foundation, or educational institution that is organized and operated primarily for scientific, literary, or educational purposes to any member of the armed forces, and the benefits thereof may be accepted by him—

(1) in recognition of outstanding performance in his field;

(2) to undertake a project that may be of value to the United States; or

(3) for development of his recognized potential for future career service.

However, the benefits of such a fellowship, scholarship, or grant may be accepted by the member in addition to his pay and allowances only to the extent that those benefits would be conferred upon him if the education or training contemplated by that fellowship, scholarship, or grant were provided at the expense of the United States. In addition, if such a benefit, in cash or in kind, is for travel, subsistence, or other expenses, an appropriate reduction shall be made from any payment that is made for the same purpose to the member by the United States incident to his acceptance of the fellowship, scholarship, or grant.

(b) Each member of the armed forces who accepts a fellowship, scholarship, or grant in accordance with subsection (a) shall, before he is permitted to undertake the education or training contemplated by that fellowship, scholarship, or grant, agree in writing that, after he completes the education or training, he will serve on active duty for a period at least three times the length of the period of the education or training.