Public expenditure on defence is defined as all costs related to the function national defence according to the Classification of the Functions of Government 1999 (COFOG):

National defence includes army, air force and navy and related activities for the protection the population, military aid abroad (international peacekeeping missions) and defence policy.

Costs related to the military police are only partly included in the defence budget. Costs related to the police training mission in Afghanistan are not included in the defence budget as this mission serves no military purpose.