The action of Admiral Hall is unethical. When the Room 40 deciphered Zimmerman telegram, Admiral Hall got to know how important this information was and the greatness of deciphering enemy’s ciphertext. He got to know that Germany will begin his plan in two weeks, but he chose not to tell America immediately. However, when the allies wanted America to join the war, Admiral Hall had to tell America this information. Hall did not want to provide Zimmerman telegram to America, but he finally did, so why didn’t tell America earlier? Hall could evaluate the cause and effect or ask for the intention of America earlier. Admiral Hall made a decision that made no sense since his wish of not letting Germany know they has deciphered the text is disclosed finally. He used the hand of Mexicans to try to hide this information, but he could choose to do this as soon as he got the decipher text. Hall made a decision that may cause more problems. The Zimmerman telegram provided the information that the Germany will initiate the attack in two weeks, but to be prepared for the attack, America needs more time. Two weeks are short but still valuable, but Hall’s decision shorten this time and may cause more casualties. Thus, the decision of Admiral Hall is unethical.
It's important to take into account the circumstances of a situation. In times of war, different standards are often applied to domestic and foreign policy as countries are working in their best interests to defend their home front. In terms of the Zimmerman telegram, I think it was a strategic move for Britain to not reveal its contents to President Wilson. Had Britain not kept the information in the telegram a secret, Germany would have discovered that their communication system had been cracked. As a result, they would have come up with a stronger, more secure, method of encryption, making it much harder for the Allies to intercept their messages. In turn, it is possible that the Great War would have continued for much longer, and more lives would have been lost in the end.
Despite the United States claiming a policy of neutrality, it was obvious they were supporting the Allies. The British knew the Americans were on their side. Because of this unspoken alliance, I believe that if the United States were truly in a path of immense crisis presented by unrestricted U-boat warfare, the British would have notified President Wilson. Because the dangers presented weren't catastrophic, it was a good choice for the British to keep their knowledge to themselves.