Initially when the previous studies were done, the two countries that were pointed at were North Korea and Iran. Well, here today, no one is pointing at Iran. Why aren't they pointing at Iran? It's that Iran is no longer a threat in this area, or that it didn't have the capability such that it would have become a threat. That's not because ballistic missile defence works better, but because there was a huge international multilateral effort to provide Iran with both positive and negative incentives to back off the offensive nuclear weapon track.
Therefore, the international community now has significantly reduced a potential threat from Iran in the future. Likewise, it's worth pointing out that North Korea doesn't yet have the ballistic missile capability that would get them reaching North America. As for their nuclear capability, they exaggerate it greatly.
The evidence would suggest, in my view, that if you look at the absolute unreliability of the American missile defence system.... I mean, you have former directors recently writing and acknowledging that the radar system cannot distinguish between decoys and real ballistic missiles, so even a rogue state can defeat the system by having a couple of decoys. There is no radar that can do this, and it's not on the drawing board right now.
I'm not in any way suggesting that we should not be concerned and that we should not do everything we can to deal with the potential for North Korea to continue down this road, but it seems to be that there are more effective ways to do it, and we have a very powerful example before us in terms of Iran on how to do it right.