The September 6th edition of The Economist included an article titled The Unsheltering Sky which evaluated the prospects of missile defense of the US from nuclear attack. The article concluded that such prospects look “doomed.”
Though the article is well-written, it seems to me that the danger is great enough to justify great expense. Putting up space-based orbital interceptors would be a fairly effective way to neutralize a small-scale attack, and such a system would protect the entire world, not just the US. It would have to be paired with a satellite inspection system to ensure that no one would hide a nuclear weapon inside a non-military satellite. Also, such a system could be overwhelmed by multiple weapons or sophisticated evasion or decoy systems. Nevertheless, though it wouldn’t be foolproof, I think it would be worth the cost. After the first use of nuclear weapons to mount an EMP attack, there is likely to be enough political capital to make this investment. Let’s just hope we are not the target of that first attack.