US Edition 
US and South Korea plan simulated nuclear strike on North Korea
Updated plans would help them prepare their defenses against a potential nuclear strike from Pyongyang
South Korea and the US are considering a military exercise that would simulate a pre-emptive strike against North Korea's nuclear weapons capabilities.
In November, the two governments agreed upon an updated set of plans to defend South Korea from missile, nuclear, chemical and biological threats. Known as the 4D Operational Concept, the plans are designed to detect, disrupt, destroy and defend the South from threats posed by the North.
The additional capability would be on top of the military hardware that South Korea has asked its closest security partner to provide.
In the wake of Pyongyang's fourth underground nuclear test on January 6, however, Seoul and Washington are examining the possibility of conducting manoeuvers to extend the reach of the plan, the Chosun Ilbo reported on Thursday.
"The two countries are discussing ways to reflect parts of the 4D concept during the joint annual exercises in March and then to develop it as a full scale operational system", an official of the defence ministry in Seoul told the newspaper.
Analysts say the two governments - along with others in the region - will have drawn up contingency plans for a number of possible scenarios on the Korean peninsula, including indications of an imminent nuclear strike, an invasion of the South with conventional forces or the collapse of Kim Jong-un's regime.
One situation that military planners are particularly concerned about would be the current regime imploding but a number of factions - potentially armed with nuclear or other non-conventional weapons - jostling for power.
"North Korean assets that are capable of waging nuclear war will obviously be of the highest priority", Lance Gatling, a defence analyst and president of Nexial Research Inc., told the Telegraph.
"These will be the mobile launch tractors that the North has for its tactical medium-range ballistic missiles, which can reach targets in South Korea and Japan", he said.
"They will also be targeting the openings to underground facilities where weapons are stored in preparation for launch, although it can be very difficult to find all these sites".
The US has said it will "not accept North Korea as a nuclear armed state".
Pyongyang has in the past condemned joint US-South Korean military exercises as provocation and preparations for an invasion of the North. It is likely to react angrily to suggestions that its perceived enemies are preparing a first-strike capability.