Office for Foreign Relations and Information 

The international cooperation between intelligence services is an important tool of gathering information. It ranges from courtesy contacts, through intelligence diplomacy, mutual provision of certain information to direct and intensive cooperation. The intensity of concrete cooperation depends on the partner and the issue, i.e. on the extent to which the both sides perceive the problem as common. LIAISON is relatively cheap but it depends on the willingness of the other side.

Source: Petr Zeman - lectures, trainings and public speeches