- Air and Missile Defence Committee (AMDC)
- AGS (Alliance Ground Surveillance)
- ACO (Allied Command Operations)
- ACT (Allied Command Transformation)
- Arms control, disarmament and non-proliferation in NATO
- African Union in Darfur (Sudan), Assisting the -
- AWACS: NATO’s 'Eye In The Sky'
- Article 5 ("Collective defence")
- Article 4 ("Consultation process")
- African Standby Force, Contributing to the establishment of an -
- Auditors for NATO (IBAN), International Board of -
- Air Command and Control System (ACCS), NATO
- Air Traffic Management Committee (ATMC)
- Afghanistan and NATO
- African Union (AU), NATO assistance to the -
- Australia, NATO cooperation with -
- Air and Missile Defence, NATO Integrated -
- Afghanistan, NATO's Senior Civilian Representative in -
- Armenia, NATO’s relations with
- Austria, NATO’s relations with
- Azerbaijan, NATO’s relations with -
- Arms control, NATO’s role in conventional -
- Active Endeavour, Operation
- Agencies and organizations
- Archives Committee, The -
- Atlantic Treaty Association and Youth Atlantic Treaty Association, The -