kwaigonegin
Colonel
It is a question of strategy. Given limited resources, which is always the case, how should a military expend the resources for the greatest return for the national interests. And what would be the likely response by the adversary and how would it change the strategic calculation.
We are not talking about defending against attack with multiple missiles here, we are talking about defense against MIRV. NK is nowhere close to the stage where they have the miniaturized warhead and missile technology necessary for MIRV. Iran is of course much further behind, especially in light of the recent deal.
Both Russia and China obviously saw the US missile defense as a threat to their deterrent capability to protest. That is especially true in case of China, which only deploy a minimal deterrent force with clear no first strike policy. China apparently felt threatened enough by the US missile defense development to began MIRV deployment on a few of its DF-5 missiles recently. Now this news about contract to develop defense against MIRV. One can only draw one logical conclusion.
Now we have to remember most analysts in the field assume that China had the technology for MIRV for many years but never deployed until now. Clearly China doesn't want to enter into an arms race and has deferred deployment until development in the US threatened its minimal deterrence force. Should the US continue it MIRV defense research, we can only assume that China will deploy larger number of MIRV to overwhelm the defense, something well within its capability.
So we are left asking what is the point of US MIRV defense research? It can't possible defend against Russian missile force nor can't it realistically defend against China which already have the technology and resources waiting for deployment. It doesn't make the US more secure against NK or Iran which doesn't MIRV technology can are not likely to have that technology in the near future. The only result would be a renewed arms race that will make all nations in the world less secure, and the only ones that profit are the arms makers who get the contract.
R & D in missile defense is always an ongoing process. It's not about having a solution today but rather keeping it ongoing to improve the defenses of the homeland. If you only start r &d by the time an actual threat appears it would have already been too late.
Some of the research may yield results that can be integrated into current subsystems w/o deploying it in it's entirety.
Personally I think the greatest threat from WMD to the US homeland wouldn't come from exoatmospehric vehicles but rather in the back of a u-haul or inside an old rusty cargo container.