Maybe because ROK wants to reconcile with the DPRK and ROK knows that they probably arent going to be the target of any of DPRK nuclear weapons.
The ROK and the US view the position from two separate vantage points.. for the US it is a proliferation issue and to the South.. it's.. well.. not that ****ing important..
The ROK has a greater fear of the US going off and doing something like strategic bombing, which would probably result in the invasion of Seoul than they do an unprovoked attack by DPRK. Maybe some in the ROK even look at DPRK nuclear weapons as a possible benefit when the peninsula is finally reunited. The ROK/US alliance does not necessarily have the same qualities it did when it was first formed. Walk down the street in Seoul and ask anyone 30 and younger what they think of US policy and the alliance.
At the very least, China is definitely looking to disturb the balance of power in the region and lesson US influence. Things like building aircraft carriers just scream power projection. China doesnt want the DPRK regime to collapse and result in millions of refugees on its border. It also doesnt really want reunification which could result in US troops stationed too close to its border.
Regime survival is the most important factor for the DPRK. Find out what brinkmanship is.
I just lived for a year in Seoul going to the top private university in Korea, taking nothing but political science and international relations courses.
BAM!!
