According to the directive:
This Directive incorporates the essential provisions of reference (a) and outlines responsibilities and functions, reference (b) , that are relative to appropriate security measures and procedures to counter the threat posed to U.S. defense and other sensitive facilities from overflights of U.S. airspace by foreign civil aircraft.
The Black Vault filed a Mandatory Declassification Review (MDR) request for this record, which was previously unreleased. In a successful case, the entire directive was declassified and released. It is available below.