What are the chances that the United States will someday launch a pre-emptive strike (likely not an invasion, but a combination of bombs and commando raids) to prevent Iran from going nuclear? Given our current troubles in Iraq, such a strike seems improbable. But as Iran moves closer to nuclearization, and the public realizes the full implications, I think the chances of war increase considerably. Having said that, the odds are still against a strike. Without a full-scale invasion and occupation, a limited strike would mean ongoing conventional war with Iran, terror on American soil, and huge ongoing disruptions in the West’s oil supply and economy. On balance, the implications of a nuclear Iran are so bad that war may be necessary anyway. But at this point you’d have to allow that America’s willingness to go to war to prevent Iran from obtaining nuclear weapons is limited. So let’s say that the ultimate chance of an American pre-emptive strike on Iran’s nuclear program is around 25 to 30 percent, at best.

Given that, whether you favor a pre-emptive attack on Iran or not, we as a nation have got to begin preparations right now for a post-proliferation future. As I note in “Our Fallout-Shelter Future,” my piece today on NRO, anti-missile defenses and the entire panoply of 1950′s-style civil defense mechanisms (everything from fallout shelters and large-scale urban evacuation plans to duck-and-cover “retention drills”) become necessities in an environment when opponents have only a few missiles, and where a small nuclear devise can be delivered by terrorists. Those who strongly oppose war with Iran can show they are serious about America’s defense by supporting a major expansion of our anti-missile systems, and the reinstitution of traditional civil defense mechanisms. But even the most pro-preemption hawk needs to realize that, in the current political environment, taking prudent steps now to prepare for a post-proliferation world is a must.

So take a look at Melanie Kirkpatrick’s timely piece, “Star Warrior.” Note that, recognizing the new threat from North Korea, Japan is already buying some of our anti-missile technology. (I love that some of our systems were designed with the help of Nascar.) It’s obvious from Kirkpatrick’s piece that our current missile defense capacity needs expanding. Not only do we need more missiles and more emplacements, we’ve got to develop laser and space-based systems. We may also need to abrogate or withdraw from the 1972 ABM Treaty, which may have made sense during the Cold War, but certainly does not in a world of terrorist friendly nuclear states. (Yet even at this late date, abrogation of the ABM Treaty could bring trouble with Russia.)

Rich Lowry was on this issue back in June, when the North Koreans tested their missiles. (See his “Shot Down.”) Rich explains why, in the current environment, an anti-missile system actually serves as a stabilizing force. Looking to save money, no doubt, the Republicans slightly pared back the Bush administration’s recent request for missile interceptors. Unfortunately, times have changed. The likelihood of a nuclear Iran means that we must now sharply expand our missile defense capabilities. By the way, Kirkpatrick notes that an Iranian representative was present at the recent North Korean missile test. Given their established network of cooperation, it is all-too-possible that Iran’s acquisition of nuclear weapons will be speeded up through the purchase of nuclear materials from North Korea. (Surely Saddam would have been next in line at Korea’s nuclear supermarket, were he still in charge.)

In the current environment, responsible Democrats and Republicans–especially those who oppose a preemptive attack on Iran–need to push for expanded missile and civil defense systems right away. Given the lead times for research, development, and deployment, we have no choice but to begin today. Iran will go nuclear anytime between now and five-to-ten years from now (I suspect we’re talking about just a few years from now, if not sooner). Yet it takes as long as five years just to put an anti-missile site in place.

In one respect, however, I would hold back. Rich reports that the Republican House axed funding for an anti-missile emplacement to protect Europe from an Iranian bomb. Well done. I have no doubt that Europe badly needs such a site–and the sooner the better. But they ought to pay for it themselves.

Does our anti-missile system actually work? As I note in today’s piece, even a leaky and imperfect system would matter, with the stakes of a single hit so high, and also as a deterrent to launch that our opponents would have to take into account, even with no guarantee of a knock-down. Nonetheless, it’s critical that we achieve at least some level of credibility for our anti-missile weapons, and that is still somewhat in doubt. Secretary Rumsfeld has just noted as much.

The fact that we’ve already deployed anti-missile defenses before fully confirming their operability shows that we are already in significant danger. So will our anti-missile defense system really work? You’d better hope so.