Concise AACR2: 56. DIRECT OR INDIRECT SUBORDINATE ENTRY

If a subordinate body or government agency to be entered subordinately (see rules 54–55) is part of another subordinately entered body or agency, omit the intervening body or bodies unless the heading would not provide adequate identification without them.

If a government agency is part of a major armed service, enter it as a subheading of that major armed service.