There is a great saying about warfare that can apply to any military operation from war to peacekeeping and disaster relief that goes to the effect of: 'Amateurs talk strategy, generals talk logistics'. The truth behind the phrase is that a country's military can have the best fighter jets, best tanks and best trained forces in the world, however all that means nothing if you can't move those forces to where they need to be, do it quickly and once there keep them provided with everything they need to live and operate (fuel, food, water, ammunition, part parts etc).
If you can't do those basics then let's face it, you can have the most high tech jet in the world, but the only thing it will be able to do is look cool on the runway. That art - logistics - is the key behind military success. So understanding how logistics works and what armies require to fight is perhaps the most important factor in trying to decide whether a country is serious about using military force.
This simple factor, looking at the movements of military supplies is the main reason why those observing the situation in the Korean peninsula do not believe that a North Korean attack is imminent. That is not to say a war could not happen due to miscalculations by either side that lead to a sudden escalation of violence. However for the North (and therefore the Kim regime) to have any hope of surviving a conflict they would likely look for a quick military success then try to negotiate a peace from a position of strength before any build up for a massive US/South Korean counter attack could take place.
For the north to launch a deliberate full scale attack - as opposed to limited scale cross border raids - there would need to occur a massive and quite observable movement of the fuel, ammunition, food, water, air defense units to guard against preemptive strikes etc towards the border with South Korea. All this movement would be quite observable to satellites and other other intelligence gathering methods. The sudden and unusual movement of whole units and the ammunition, fuel, communications equipment etc that they'd need to move, fight, and coordinate with each other would be the real indication that something sinister is afoot. Why? Because you don't need those things to guard a border, but you do need them for an attack south.
With news coverage of past wars focusing on precision airstrikes and front line combat you rarely get a chance to see what's behind the curtain making it all work. Counter intuitive as a it may be to those brought up on first person shooter X-box games or someone just looking at a table of relative military strengths (comparative numbers of tanks, fighter jets etc) in war combat is for the very few.
Numbers are deceptive. In the March 2003 invasion of Iraq the unit that spearheaded the US Army's thrust through the desert to Baghdad was the Third Infantry Division. On paper it's strength is about 20,000 troops with hundreds of tanks, armoured vehicles and helicopters. However each tank needs a truck to supply fuel to it, it needs a separate truck to provide it ammunition to fight. It's crew needs water and food, radios need batteries etc. The trucks or helicopters that supply those need drivers, they need troops to protect them en-route they need fuel themselves etc, it goes on and on.
In fact of the approximately twenty thousand soldiers in that 'Infantry Division' the commander was quoted that they had a mere 1,200 actual infantry - the foot soldiers that do ground fighting. If you add in crews for the tanks and artillery. you maybe get 3,000 or 3,500 at most out of 20,000 that would actually fight. The rest are there to provide those few what they need to live, move, eat and fight - essentially every basic necessity of life, on the battlefield and off.
It can be reasonably guessed that North Korean units would not require the same type of logistics train that US or other Western armies do, however they still need to move, eat, shoot, and fix the things that break down. A movement of 10,000 troops for an attack south (and any full scale attack would be much larger) would even with the assumed lighter logistical requirements of the 'Democratic People's Republic' forces likely require the use of an additional twenty thousand troops to move the assault forces and bring them what they need. All of which would be quite easily noticed and monitored. This hasn't happened yet. Otherwise alarm bells would be going off and American and South Korean forces would surely be under great pressure to launch a preemptive attack to try to minimize the effect of any North Korean strike.
In the first Gulf War the United States poured just over half a million troops into Saudi Arabia in the build up to Operation Desert Storm. This build up - Operation Desert Shield - began in August 1990 with units and equipment still arriving right into February 1991 when the war was already well under way. Why so long? It wasn't necessarily moving the fighting troops and their equipment that took time. It was bringing everything they needed to live and fight that took much of the effort. Of the over half million troops deployed, maybe sixty to eighty thousand at best were what you could call 'front line' forces, the rest were to keep the machine going and ensure it had everything it needed to move, communicate, fight and live.
To put it into perspective, in that six month time span the United States military did the equivalent of moving a mid sized city like Calgary half way across the world, and set it up fully functioning in the desert with everything it would need to operate.
It is THIS logistics capability that is the true strength of the US Armed Forces. Most Western military forces have special forces, high tech fighter jets and satellite guided bombs. But no other country can take that many forces, move them that far around the world, and keep them continually supplied everything they need. Not China, not Russia, not Britain, France or any combination there of. In fact in every major coalition conflict (The Gulf War, Iraq, Afghanistan, Libya, Kosovo etc) allied countries have a some point relied on the US's airlift, intelligence or some other component of the American logistical chain to get what they required.
Finally, in all likelihood the warlike talk coming out of the North Korean capital could just be noise to help establish a name for new leader Kim Jong-un; however it is also likely being done to try and coerce a different type of logistical support. Food aid and the easing of international sanctions.
