Steven Den Beste has a few fascinating posts on nuclear proliferation, and Iran and North Korea specifically. In the most recent post, he briefly describes the nuclear-acquisition precedent that has been set over the past decade, as it relates to our desire to deter our enemies:
That establishment of a deterrent will be part of Bush's calculation. The decision on those attacks, should it come to that, will in part be based on the consequences specifically of those cases. But it will also be based partly on whether it's necessary to establish an object lesson for other nations who might be contemplating the same thing.SDB doesn't mention it, but I think he knows that the nuclear cat is out of the bag, so to speak. He's right, it is difficult to enrich fissionable materials -- and it's especially difficult to hide the process -- but India and Pakistan did it handily enough, and it's only getting easier. In time, maybe a decade or two at most, every country that wants to have nuclear weapons will be able to either build them or buy them, that that will fundamentally alter the balance of power in the world.
The big problem here is India and Pakistan. They did the same thing and succeeded, and it's not likely at this point that there's going to be any significant attempt by us to try to force either or both of them to disarm again. Indeed, Israel is perhaps an even more important case. They represent a positive example to those attempting to develop nukes, by showing that once you've done so, you probably won't be forced to disarm again.
South Africa did, but that was pretty much voluntary. If it had refused to, it's not clear the kind and extent of pressure which would have been applied.
A lot of pernicious precedents got set in the 1990's; part of why we're in a mess now, and part of why things have gotten as bloody recently as they have, is that we're having to change the perception of those precedents. That means in some cases we're having to perhaps use a stronger military response than might otherwise have been needed, because we need to set an example for the future. That's going to be part of Bush's decision this time, too.
Conventional military force serves as the ultimate recourse (and foundation) of diplomacy, but nuclear weapons give their owner near complete immunity from conventional warfare. In order to win a war you need to put troops on the ground, and any army is vulnerable to a single van (or ambulance) carrying a nuclear device. North Korea and Iran are making big gambles by trying to construct nuclear weapons, but if they are successful they will win major victories: although the United States may be considering military options against their hostile regimes now, if and when they acquire nuclear weapons that possibility will be essentially off the table. Just as nuclear weapons deterred the United States and the Soviet Union from all-out war for 40 years, these rogue nations will successfully deter the United States.
What then? Iran will buy itself virtual immunity for its support of Hizbollah and its encouragement of terrorism around the world, particularly against Israel. The need for nearly-plausible deniability will vanish, and the marginal cost for stopping each of their terror attacks will increase greatly for the United States and Israel. How many busses will need to be blown up before Israel can retaliate, knowing that it risks nuclear escalation? Alternatively, what if Iran slips a device to some terrorist group that then uses it to blackmail Israel? (It's unlikely that Iran would attempt to blackmail Israel or the US directly, since such blackmail would invite immediate nuclear retaliation by either country.) A terrorist group that's hiding within Israel and can't be found won't be deterred by nuclear weapons.
Blackmail is a way of life for the North Korean government. They've been using the threat of a conventional infantry/artillery invasion over the DMZ into Seoul for 40 years to force the world's powers to buy them off. The North Korean government would have collapsed long ago without the oil and food they've extorted from the United States and others over the decades. Now that those payments have nearly stopped, the North Korean government is on the brink of implosion and believes that if they are able to attain nuclear weapons they'll be able to force us to acquiese to their preposterous demands. It's unlikely that they would be crazy enough to resort to direct nuclear blackmail, but their standard threat of conventional attack becomes much more difficult to thwart if it's backed by nuclear weapons
Not to mention the fact that North Korea has recently tested missiles that could deliver a warhead to Japan. Japan doesn't have nuclear weapons (because the US bears the primary responsibility for Japan's defense), but if North Korea gets them then Japan will insist upon it. China certainly wouldn't like to face a nuclear-armed Japan, and so China has an added incentive to defuse the North Korean situation.
However it plays out, the world gets much more complicated and the United States will be in a weaker position than it's in today. Total nuclear proliferation is only a matter of time, and I hope that someone is giving some thought as to how the world will operate once every nation has nuclear capability.
It's an interesting thought experiment. If everyone has nuclear weapons then conventional forces may become entirely obsolete. Any conventional attack could immediately escalate to nuclear, so what would be the point of maintaining an army? It could make the world very peaceful, but it could also result in an unstable equilibrium -- like a soda bottle balanced on its mouth, it's steady, but a single wobble could bring the whole system crashing down. Unless some new technology is created that can nullify ground-delivered nuclear weapons (as opposed to mere missile defense), it's hard to see how the current world order can hold sway for much longer.
I wanted to add that there's a race on between nuclear proliferation and the spread of democracy and freedom. Democracies don't go to war with each other as a general rule, even when they have nuclear weapons. It's the dictators that we have to be scared of. So, if democracy can spread more quickly than nuclear weapons do, everything should be peachy. It just doesn't seem inevitable to me.