Sixth Air Force had the responsibility for tracking down submarine wolfpacks, which consisted of groups of three of more subs attacking Allied shipping using a strategy now known as "Search and Destroy". As most shipping in the Caribbean was not in defensive convoys, aerial surveillance of the area was crucial to their safety. However, in the fall of 1942 the German Navy changed tactics and reduced their submarine activity in the Caribbean region to concentrate its activity on the North Atlantic convoy route and the approaches to northwest Africa. With the withdrawal of submarines from the Caribbean region the Sixth Air Force concentrated its efforts as a striking force on its primary function of guarding against possible attacks on the Panama Canal.