Lieutenant James D. Harden of the US Army Air Forces did not respond to the messages, and turned away and notified his base of the situation. The senior officer on duty that day, Captain Robert C. Richardson III, who claimed later that he did not know that this was a Red Cross-sanctioned German rescue operation, ordered the B-24 to "sink the sub". The patrolling bomber loaded with depth charges and bombs reported that the submarine had a white flag with a red cross and they had unsuccessfully challenged the submarine via radio to display its national flag. The submarine blinked via signal light what the bomber crew understood to read "German Sir". The bomber crew asked Ascension Island what to do next.