Lieutenant James D. Harden of the US Army Air Forces did not respond to the messages; turning away, he notified his base of the situation. The senior officer on duty that day, Captain Robert C. Richardson III, who claimed that he did not know that this was a Red Cross-sanctioned German rescue operation, ordered the B-24 to "sink the sub". Richardson later claimed he believed that the rules of war at the time did not permit a combat ship to fly Red Cross flags. He feared that the German submarine would attack the two Allied freighters diverted by the British to the site. He assumed that the German submarine was rescuing only the Italian POWs. In his tactical assessment, he believed that the submarine might discover and shell the secret Ascension airfield and fuel tanks, thus cutting off a critical Allied resupply air route to British forces in Egypt and Soviet forces in Russia.