A nation allied with the U.S. in a current defense effort and with which the U.S. has certain treaties. For an authoritative list of allied nations, contact the Office of the Assistant Legal Adviser for Treaty Affairs, Office of the Legal Adviser, U.S. Department of State, or see the list of U.S. Collective Defense Arrangements at www.state.gov.
Sources:
CNSSI 4009-2015
from
CNSSI 4005