Do you really think that should there be a next "world war" that China, or whomever our opponent is, is going to be so kind as to allow us that HUGE military advantage simply because they signed some silly piece of paper at some point? Don't be so naive.
You know, I really don't understand the whole concept of weakening the United States military simply to "make freinds." It is not going to work.
The ONLY reason that other countries want US to sign this thing is because they know that we ARE the leader in space and they would like a more fair playing field if anything happens. Well guess what! War is NOT fair. Get over it.