On 22 November 1939, the Head of "Luftwaffe" (German Air Force) intelligence Joseph "Beppo" Schmid presented his "Proposal for the Conduct of Air Warfare", which argued for a counter to the British blockade and said "Key is to paralyse the British trade" by blocking imports to Britain and attacking seaports. The OKW ("Oberkommando der Wehrmacht" or "High Command of the Armed Forces") considered the options and Hitler's 29 November "Directive No. 9 – Instructions For Warfare Against The Economy of the Enemy" stated that once the coast had been secured, the "Luftwaffe" and "Kriegsmarine" were to blockade UK ports with sea mines, attack shipping and warships, and make air attacks on shore installations and industrial production. This directive remained in force in the first phase of the Battle of Britain.