Well, you may be right, it is just a matter of interpretation. But when it comes to defence in international relations it is basically a variation of Prisoner's dilemma[1]. It doesn't matter what reasons USA has to develop ABM. Russia, China, NK and everyone else will never choose to disarm when their oponent is arming.
[1] https://en.wikipedia.org/wiki/Prisoner%27s_dilemma#In_intern...