On 1 August 1940, Hitler instructed intensified air and sea warfare to "establish the necessary conditions for the final conquest of England". From 5 August, subject to weather delays, the "Luftwaffe" was "to overpower the English Air Force with all the forces at its command, in the shortest possible time." Attacks were then to be made on ports and food stocks, while leaving alone ports to be used in the invasion, and "air attacks on enemy warships and merchant ships may be reduced except where some particularly favourable target happens to present itself." The "Luftwaffe" was to keep sufficient forces in reserve for the proposed invasion, and was not to target civilians without a direct order from Hitler in response to RAF terror bombing. No decision had been reached on the choice between immediate decisive action and a siege. The Germans hoped the air action would force the British to negotiate, and make invasion unnecessary.