But that doesn't necessarily work as an argument against NMD. It only works against NMD as currently conceived.

I see myself as someone who does not support NMD, but who does support missile defense. I have no idea how others see me - on this board I probably come off as a left wing-nut.

But what I mean by the above is that I think missile defense is a great idea. But I think NMD is being sold under false pretences. It's obviously not going to stop terrorists and the 'rogue states' that support them.

So who is it really designed to stop, what is its real purpose? China has a small number of nuclear missiles, so perhaps it could stop a Chinese nuclear attack. This is not a bad idea, except for one thing.

China is rapidly acquiring American technology, has an infant space program, and will sooner or later build more missiles if it believes these are needed to counter-balance NMD. More to the point, the Sino-Russian alliance against American hegemony may mean that China will receive Russian help in some of these endeavors.

For strategic purposes Russia may not feel it can afford to take the chance that NMD might deliver on at least part of its promise. So how might Russia respond to NMD? Same as China: Build more missiles. But that's expensive, and Russia's economy is in terrible shape - no wonder Russia doesn't want NMD.

As if a new arms race, accompanied by Cold War II, the Sequel, isn't bad enough. It gets even worse if the NMD doesn't work as promised. Opinions go either way on this point, so I won't argue it here and now.

So continue the research, and adopt a more modest program. A scaled back version of NMD which doesn't require deploying a whole new space-based infrastructure might be cheaper. And might also one day be used as one layer of a many-layered defense. Rome wasn't built in a day. Neither, apparently, will a missile shield.

A more modest program doesn't preclude going forward with something more ambitious at a later date. But it may avert a new arms race. For awhile. Maybe the world can figure out how to live without a Cold War during that interval.

In the meantime, America and the West get better at shooting down missiles. Those opposed to American hegemony likewise work to improve their own weapons - missiles, suitcase nukes, bioweapons. And life goes on as it always has.

One step up, two steps back.