Unlike the North Atlantic Treaty Organisation (NATO), ANZUS has no integrated defence structure or dedicated forces. Nevertheless, Australia and the United States conduct a variety of joint activities. These include military exercises ranging from naval and landing exercises at the task-group level to battalion-level special forces training, assigning officers to each other's armed services, and standardising equipment and operational doctrine. The two countries also operate several joint-defence facilities in Australia, mainly ground stations for spy satellite, and signals intelligence espionage in Southeast and East Asia as part of the ECHELON network.