|NMD is a political program, not a useful military one. It gets support in Washington because no one wants to be accused of leaving America vulnerable to missiles from "rogue" nations, whatever that means. But the fact is it is unnecessary, and useless against real threats.
There is in fact no threat of an ICBM launch against the U.S. Currently only two countries can even attempt it--Russia and China. They have been able to do this for decades and have never done so, nor will they. It amounts to suicide, which is not in their interests.
And that is also true of the "rogue" states. The simple fact is that only a nation-state can build or launch an ICBM (by the way, none of these "rogue" states has anything that is remotely close to reaching the US). Even if a non-state actor got one, it has to launch from somewhere, and we would detect the launch. So even if the state in question did not perform the launch, by allowing it it becomes a big fat target. As with Russia or China, such a launch is suicide. Even "rogue" states have no interest in suicide.
If you want to hit the US with a nuke, you do not use a missile--only a complete fool would do that. You put one in a small fishing boat and sail it into New York harbor, or LA, or San Francisco, or Savanah, and then set it off. No trace, no retaliation, plenty of destruction. And NMD is 100% useless against that.
We are preparing to increase defense spending by at least 50% (when we already outspend the next ten powers combined) to provide a defense against a threat that does not exist. Foolish, and we will bury ourselves in overspending.