While Admiral Hall had some justification for his actions, his decision to keep important information from President Woodrow Wilson and the American government was unethical in the sense that passing that information on could have potentially spared lives. That being said, Admiral Hall had some reasonable justifications for acting in the way that he did. Hall intended to hide the fact that Britain had cracked Germany’s in order to prevent them from changing their cipher. He also came up with a plan to make it seem as if the information had leaked from Mexico so that Britain was not suspected of intercepting the message. Even so, deliberately keeping important information from the US was unethical.
The Zimmermann telegram brings up an incredibly controversial and open-ended debate: can it be justified that the lives of a few be deliberately risked to save the lives of more? The Zimmermann telegram was specifically about unrestricted use of German U-Boats and US involvement in the war, but it ties into overarching themes of wartime sacrifice and the value of truth within government and military. I believe that such sensitive information should be shared as soon as possible with all of those who may be affected by it. Granted, if it had not been for the ingenuity of Britain’s Room 40, Admiral Hall would not even have access to the information which he withheld from the United States. In the end, though, he did have access to this information and knowingly and unethically withheld it from the United States.