Thats like saying CNN sources are clued to the real powers making these decisions
Other than war merchants many South Koreans esp. the young are weary of 70 years of war games and would welcome deescalation and not feel less safe by advances in diplomacy
Chosun-Ilbo is as close to an official government news source as it gets. Think of them as the South Korean equivalent of Sean Hannity. If they said that this caught the South Korean government and military by surprise then it's clear they had no idea Trump was going to do this.