There was a time when missile defense was considered an absurdity, with all the liberal types of physicists lining up and saying, "It will never work, and you will scare the Russians too. Just be hostages."
The missile races underway in the international system are proof of one thing: Ronald Reagan was fundamentally right to take missile defense seriously, in spite of all the critics.
That doesn't mean that the Ballistic Missile Defense Agency doesn't have issues, but it does mean that more and more states acquire the ability to hit the United States with nuclear weapons, having a backup other than just genoiciding them, is wise.
Prompt Global Strike looks a lot better too, as the ability to bring on a time urgent high probability single shot kill is the best offense to proceed a good defense, if defense as they say, wins championships.