32 CFR 154.6 - Standards for access to classified information or assignment to sensitive duties.
(a) General. Only U.S. citizens shall be granted a personnel security clearance, assigned to sensitive duties, or granted access to classified information unless an authority designated in Appendix E has determined that, based on all available information, there are compelling reasons in furtherance of the Department of Defense mission, including, special expertise, to assign an individual who is not a citizen to sensitive duties or grant a Limited Access Authorization to classified information. Non-U.S. citizens may be employed in the competitive service in sensitive civilian positions only when specifically approved by the Office of Personnel Management, pursuant to E.O. 11935. Exceptions to these requirements shall be permitted only for compelling national security reasons.
(b) Clearance and sensitive position standard. The personnel security standard that must be applied to determine whether a person is eligible for access to classified information or assignment to sensitive duties is whether, based on all available information, the person's loyalty, reliability, and trustworthiness are such that entrusting the person with classified information or assigning the person to sensitive duties is clearly consistent with the interests of national security.
(c) Military service standard. The personnel security standard that must be applied in determining whether a person is suitable under national security criteria for appointment, enlistment, induction, or retention in the Armed Forces is that, based on all available information, there is no reasonable basis for doubting the person's loyalty to the Government of the United States.