I agree this is not Bush’s fault, although I don’t like how he’s handled it.
First, it’s a tough little problem to solve. Provided the attack is from someone with fairly advanced technology, each missile will have multiple warheads and several decoy warheads (along with various countermeasures). You will need one missile to intercept each warhead, provided you can hit 100%. And because they chose not to use an explosive warhead (a poor decision IMO) close isn’t good enough – you have to actually hit the inbound warhead to destroy it with kinetic energy. Repeat this for each missile. And you have to bat 1.000 -- one miss and it’s going to get real warm somewhere.
Secondly, I’m not at all convinced that the people working on this, including the prime, are up to the task. The problem is there aren’t a lot of rocket scientists left. Herds of computer guys, radar guys, engineers, etc. but hardly anyone that knows which end the smoke comes out. For example, in some of the early tests they had problems with the stages separating. That’s just rocket science 101 --- if you can’t do that, you need to turn in your slide rule.
Finally, the fact is that Bush shut down many of the planned tests. Computer simulations are fine, but there comes a time when you just have to run the test. For political reasons, we’ll have a missile in the ground by the end of the year. But let’s hope we never have to find out if it works – because I doubt it will.