And when confronted by an aggressive state like Nazi Germany or Soviet Russia, or these days, a nuclear-armed Iran .... what, precisely will those "cost effective and imaginative" steps be? One thing is certain: it costs a hell of a lot of money to take your "imaginative steps."
Your General Re Defense Division is not going to build its missile defense from scratch in a year ... it's going to have to anticipate attacks years in advance if it wants to have any chance of countering them when the time comes. And so it'll have to shoulder a persistent military burden powerful enough and modern enough to respond to threats when they pop up. The standing army raises its ugly head once again, only this time there's no civilian oversight beyond what the Board of Directors think is good for the bottom line.
I concede that raising the stakes raises the specter of defeat, and hence calls private defense into question. There are several ways to answer you.
One, I could raise the stakes still more--as I already did earlier, anticipating this--and say, "What about Iran armed with a sun-killer bomb? What would the US military do?" The answer is, of course, that it would kiss its arse goodbye, like the rest of us.
Or two, I could observe that the Pinkertons will have nukes. After all, we're postulating that government doesn't exist in the US (but does everywhere else); that implies there will be no NRC, and hence nobody to forbid the Pinkertons' building nukes. Luckily, the Pinkertons will have a disincentive to get uppity, since Securitas and Hagana will also have some nukes. And, of course, so will Steve Ballmer and, just to keep up with the joneses, so will Larry Ellison.
Or three, I could ask exactly what motive these nations will have to nuke the US which, remember, hasn't invaded anyone since government was dissolved in the Libertarian Bloodless Coup. Like Switzerland, we would be a desirable trading partner; also like Switzerland, we would be a quiet neighbor. That being the case, your proposed nuclear threat is based on the assumption that we're dealing with a madman like Ahmedinejad or Brezhnev. Of course, we might well come to face such a madman. However, I'll point out that Russia and China will deter Ahmedinejad, since their interests do not align with his, and US trade is the main thing keeping China from starvation--especially since the 100% free trade policy after the LBC...
Your General Re Defense Division is not going to build its missile defense from scratch in a year ...
Nor is Iran going to attack in a year. The dissolution of all government after the LBC will, of course, result in a flood of classified technology hitting the open market. It will take the Chinese a while to digest it all, and meanwhile the Americans will be marketing it like crazy, as will the Japanese. Given their love-affair with technology, the Japanese would be selling personal defense force-fields within the decade; kids will be hacking their iPods to use as subspace communicators. Some weirdo at MIT will invent the phaser. In the meantime, Taiwan, Tibet and Hong Kong will all declare full statehood and independence from China, leaving the middle kingdom with its hands quite full.
The standing army raises its ugly head once again,,,
You keep developing amnesia, and forgetting that every soul in America is armed--with phasers, in fact--and will fight to the last man. If all else failed, and China nuked the crap out of the US, they'd still have to kill every breathing soul on the continent before the war was over. Which raises the question, what operational goal calls for complete extermination of your best market--the one keeping your nation from starvation? The militian obviates a standing army, precisely as the 2nd amendment intended.
only this time there's no civilian oversight beyond what the Board of Directors think
...as opposed to the amazing civilian oversight that takes place now? Thfffpt! Anything interesting going on today is classified, friend. They could tell you or me about it, but then they'd have to kill us. We oversee nothing of any significance.