Whenever (and to the extent) the Secretary of State considers it in the best interests of the United States Government, the Secretary of State may authorize the head of any agency or other Government establishment (including any establishment in the legislative or judicial branch) to appoint under
section 3943 of this title individuals described in subparagraph (B) as members of the Service and to utilize the Foreign Service personnel system with respect to such individuals under such regulations as the Secretary of State may prescribe.