WHY? Please tell me why!

I beg of you, please tell me why a country, known as the most powerful country in the world, would ever tell other countries: We won't use our most powerful weapon on another country even if they attack.
Have your own secret rules for doing what you want but...never, ever tell anybody you will not use a weapon against who ever attacks you. To tell anybody you won't use whatever you have to protect yourself( your country) is asking for trouble, if not down right dumb!
Let a "would be", "might be", "could be"' enemy think you will use anything and everything you have to protect yourself. To do anything difference is down right dumb, to say it in a nice way!
Why would I need to say this? Our president is getting ready to do just that, he is going to tell other countries the US has a set of rules for using nuclear weapons and not using nuclear weapons. BAD MOVE! VERY BAD MOVE!
Mr. President, I don't care if you are a Democrat, Republican or Independent.
Mr. President, I don't care if you are black, brown red,white, yellow!
Mr. President, please protect my butt and the rest of the people who live in the US!

Tomorrow or the next day you will hear his(the president's) words on this subject, please pay attention.
As soon as I get a copy I will post more but at this time I CAN ONLY REPORT ON WHAT I HAVE HEARD FROM A VERY GOOD SOURCE. If I am wrong I will be more than happy to report it. As a matter of fact, I will be happy to say I am wrong, I hope I am wrong>