[Astro_Bot]

Hi Peter. You seem to be a bit off in the facts ... I'll try not re-hash what Brendon has already covered; apologies if I do.

Let me first say for the record that I'm not trying to promote the threat from NK as the world's #1 problem - I thought I was done with this thread at post #2 - but the relatively uninformed views that have been posted since are keeping me involved.

Originally Posted by Stardrifter_WA

IF, North Korea does create a nuclear weapon

They have - they've conducted three successful tests, the most recent being for a miniaturised weapon, which, though not an operational warhead, is a big step closer to that goal. No-one (in the business of watching NK) seriously doubts that their goal is operational warheads.

how will they deploy it and with what accuracy,

They are developing and continue to develop ballistic missiles and periodically conduct test firings, the most recent being over Japan that allegedly put a satellite in orbit. Again, no-one (in the business of watching NK) doubts that their goal is an operational class of ballistic missiles. FYI: Taepodong-2 has a range believed to be >6,000km and further developments are in progress.

and could they get it past the missile defence shields on the US coast? And yes, I do realise that these defence shields are not totally effective,

The problem of intercepting ballistic missiles is extremely challenging. The extreme speed and (largely) exo-atmospheric flight path makes detecting, tracking and intercepting these targets a monumental task. Defence hinges on two of four stages. (1) Boost phase, when the rocket motor is burning and the target is hot and easily "seen". Unfortunately, this is well within adversary territory and lasts only a few minutes - flight time of the interceptor to the target may well be longer than the boost phase itself and chances are the ballistic missile will be above the maximum ceiling of the interceptor by the time it gets there. Still, there are efforts to try this - the Air Borne Laser being the most prominent, but after 17 years, that is still just "testing". (2) Ascent phase, when the missile gains high altitude and becomes exo-atmospheric - only initial R&D is going on here. (3) Mid-course phase, which is exo-atmospheric, when one must detect a cold target against cold space at altitudes of >>120km and hit it at >20,000 km/h with pinpoint accuracy with the window of opportunity due to interceptor downrange/crossrange overlap being very small. Very hard! The US Navy has deployed a system - it's effectiveness is unverified, though they claim to have conducted successful tests. The US Army is developing a system under the auspices of the Missile Defense Agency - it is still in a testing stage. I must emphasise the difficulty of hitting an unknown/unannounced target vs a rehearsed test target - it really is a hard thing to do. (4) Re-entry/terminal phase, when the target is within the range of land-based defence missiles, is very, very hard - the target aspect is smallest and the speed highest - this isn't considered credible for intercontinental ballistic missiles (of the type NK is developing), but against slower and shorter range missiles (speed:range is roughly proportional), it has some chance of success, and this is where those defences are concentrated.

Add to that: from 1972-2002, the ABM treaty forbade anti-ballistic missile defence developments. The US withdrew in 2002 due to "rogue state" ballistic missile developments from the likes of NK and Iran. Consequently, ABM developments are two decades behind ballistic missile developments.

however, if a strike was imminent, I am sure a lot of these missiles would be deployed, with a chance of one destroying the incoming nuke, thus mitigating the strike. Just look at the 'Iron Dome' defence shield that covers Israel.

See above. Terminal defence missiles are mostly ineffective against the class of weapon NK is developing. Even short range ballistic missiles like Scuds used by Iraq were relatively impervious to short range interceptors (Patriot batteries, though used, had little success).

Also, the US has 'tactical' nuclear weapons, as opposed to the 'strategic' nuclear weapons that North Korea is trying to develop, assuming that they are not as advanced in weapon design. A 'tactical' nuclear weapon is designed to strike military targets with high precision and are probably a low yield device, thus minimising collateral damage. And, I doubt NK have the necessary technological sophistication required to develop high precision guidance systems.

You're doubts are unfounded. They can guide a satellite to orbit (regardless of whether the satellite works) = they can put a ballistic missile on target. It's the same problem simply with different boundary conditions. Your argument about tactical vs strategic is non-sensical. All nuclear weapon delivery systems are designed to strike with very high precision. "Low precision" hasn't been a problem since the 60s era of weapons, all of which were withdrawn long ago. NK's developments show no signs of being "low precision". Tactical nukes are more readily described as those under the command of a battlefield commander delivered by non-ballistic missile means. AFAIK, the USA no longer deploys tactical nukes and I would guess that, since the demise of the Soviet Union, the Russians don't either. Hollywood, however, has yet to catch up - they seem to want to call any warhead <100kT a "tactical" nuke.

IIRC, NK has been a net exporter of ballistic missile and nuclear technology - they're more advanced in that area than most other countries, including Australia. (Obviously, there are some countries more advanced, such as USA, Russia and China).

One particular problem is who NK might sell to next - because there remains the distinct possibility of a terrorist organisation obtaining a "backpack" nuke - that's another avenue of concern from successful weapon miniaturisation.

If there was a real and credible threat of an imminent strike from NK with a 'strategic' weapon, which is designed to destroy large areas, the US would have no hesitation in deploying a 'tactical' nuke, or even a normal cruise missile, to destroy the NK missile, before it even launched. And NK would know this, and that would be a deterrent, as they would not be able to actually carry out the threat with any real chance of succeeding. China would also know this and would probably step in to prevent any real escalation of hostilities on the Korean Peninsular.

NK hasn't responded (in a manner the international community considers acceptable) to any deterrent so far, and shows no signs of doing so. Also, see below.

The US has sophisticated surveillance systems which North Korea do not have, so are in a better position to know what NK is doing.

NK doesn't need surveillance - cities don't move. Even "early warning systems" of the kind that have been around since the 60s wouldn't provide meaningful warning of a pre-emptive launch by NK against Japan or even the USA. The entire Cold War nuke deterrent hinged around not knowing if/when the Soviets would launch. That's the nature of ballistic missiles: maybe a satellite picks up a thermal bloom that could be a launch, and maybe an radar system picks up the ascent and some of the mid-course trajectory, but ICBM flight time is <30 minutes, and that's bugger all time to do anything, hence the decades-long non-reliance on ABMs and the policy of MAD. I know systems are in development, but again, it's a very hard problem - like trying to hit a tiny supersonic jet with a .22 rifle bullet - don't hold your breath.

So, I doubt NK can really do anything meaningful to carry out such a threat anyway. And, as I said earlier, I ain't worried about it and won't lose any sleep over it.

Actually, i'm not losing sleep either ... over this, anyway ... my insomnia is caused by other things. But, keep in mind that there's been a saying in the "business" for a long time: "I'm more terrified of the guy with one nuke than the guy with a thousand".

And after all that .... Good night and good luck.