The Baltic Approaches were central to the Cold War activities for NATO as well as the Warsaw Pact (WAPA). The approaches were of strategic importance for East and West. In geographic terms, control of the Baltic Approaches would require control of the territories of Denmark and Schleswig-Holstein, and control of the waters of the Western Baltic and the three straits of Øresund, Great Belt and Little Belt. In addition, control of the air space was essential.
In terms of strategic sea control, the East had the desire to get out of the Baltic in order to attack NATO shipping in the North Sea and the Atlantic. The West initially wanted access from the North Sea to the Baltic in order to deliver reinforcement to ground forces in Northern Germany. Later on the main goal was to block East from getting out because now NATO reinforcements would come from harbours at the North Sea.
Another strategic goal for the West was to maintain control of air fields in Jutland for attacks towards east, and at the same time prevent the Warsaw Pact from getting access to the very same fields which would give access to attacking Southern Norway, Britain and Northern Germany as well as the North Sea, Kattegat and Skagerrack.
Regarding territory, ground forces were necessary to maintain control over communication lines in the broadest sense and to prepare for denying attacking ground forces access, whether from the air, from the sea or by moving through Northern Germany.
All modern warfare is dependent on control of the air space. Therefore, air forces were necessary, initially during daytime, later around the clock.
In sum, control of the Baltic Approaches required control of land, sea and air. During the Cold War, NATO had two ways of organizing such control. First, until 1962, the Northern European Command (AFNORTH) had control of all with Schleswig-Holstein as southernmost area, but the emerging West German navy came under control of the Central European Command (AFCENT). This control was disputed during most of the period because strong forces within NATO wanted the Central Command to take over and let the Northern Command have control only of areas North of Denmark. From 1962, however, a new integrated command, the BALTAP (still under the general command of AFNORTH), was created for the Baltic Approaches, integrating all military forces in the area. BALTAP remained active during the rest of the cold war.