North Korea has about 100 mobile launch platforms for ballistic missiles, which could pose the biggest threat to South Korea if the regime succeeds in miniaturizing nuclear warheads.
It would be hard to detect these heavy trucks and strike them because they keep moving around.
A government source in Seoul on Wednesday said South Korean and U.S. intelligence agencies believe that the North has some 100 of these platforms for medium-range ballistic missiles such as the Scud and Rodong, which have all of South Korea within range.
There are about 27 to 40 mobile launch platforms for the Scud missiles, which have a range between 300 and 1,000 km; 27 to 40 for the Rodong missiles with a range of 1,300 km, and 14 for the Musudan missiles with a range between 3,000 and 4,000 km.
The North has an estimated 640 Scud missiles and 150 to 250 Rodong missiles.
The mobile missile launchers would make it harder for South Korea and the U.S. to launch a pre-emptive strike using the so-called "kill chain" in an emergency. A "kill chain" is the process of detecting, identifying and intercepting missiles.
The Defense Ministry has mapped out a plan to establish a 30-minute "kill chain" system by 2015. A spokesman on Wednesday said this includes ship-to-shore and submarine-to-ground cruise missiles.
The ship-to-shore missiles have a range of 500 to 1,000 km and are deployed on Aegis destroyers and Korean Destroyer (KD) vessels.
The submarine-to-ground missiles have a range of more than 500 km. The missiles have already been deployed since last year, but the ministry for some reason failed to announce this.
Some pundits believe the ministry is exaggerating the power of the "kill chain" and new missiles to calm anxiety in the wake of the North's nuclear test.
During the Gulf War in 1991, the U.S. had a great deal of trouble finding and destroying Iraq's mobile Scud missile launch platforms. It sent aircraft on as many as 1,460 sorties to hunt Scud missiles and boasted that they destroyed some 100 such missile platforms. But analysis afterward showed that not a single Scud missile launch platform was destroyed completely.
It is not impossible to detect Scud or Rodong missiles, which use liquid fuel, before they are launched, because it takes between an hour-and-a-half to three hours to fuel them up. But experts say that detecting is one thing and destroying another.
Prof. Kim Yul-soo of Sungshin Women's University said, "It's difficult to detect mobile launch platforms, and even if we do they could have moved on by the time the intercept missiles are ready to fire."