The basic question is not posed. How do we keep fear from making us create ever deadlier weapons? The primary reason the A-bomb was developed was because the U.S. wanted to be sure it was not caught off-guard by our enemies that could create their own A-bomb. Ultimately, we were the only ones that developed the Bomb and were the knowledge source for others to create their own. We are going down the same path with AI weapons.
It comes down to creating an organization that everyone can trust to help maintain peace. The U.N. was suppose to be that but it has become a toy of the dominate nations to manipulate at will.