North Korea is expected to begin the process of shutting down its main nuclear testing facility as early as Thursday. 

A North Korean official told South Korean journalists who were on standby in Wonsan on Wednesday that the dismantling of the Punggye-ri test site could begin on Thursday if weather conditions permit. 

The North has yet to unveil the official schedule of the dismantling to the journalists invited from five countries to observe the event.

South Korea's eight-member press corps arrived at Kalma Airport in Wonsan at 2:48 p.m. on a government plane from Seoul Air Base in Seongnam, Gyeonggi Province. 

The South Korean and foreign journalists left for Punggye-ri at around 7 p.m. via a special train. 

Wonsan is 416 kilometers away from Jaedok Station near the nuclear test site. Given that North Korean trains travel at an average speed of 35 kilometers per hour, the reporters are expected to arrive in Punggye-ri 12 hours later. 

It is known they will travel an additional 21 kilometers from Jaedok Station to Punggye-ri by car and on foot.