Seoul’s top security officials finalized a plan to expand South Korea’s air defense zone at their meeting Friday in the wake of President Park Geun-hye’s talks with visiting U.S. Vice President Joe Biden.

A sophisticated style of diplomacy will be needed to deal with the aftermath of the formal announcement of the expanded zone, which is expected to come on Sunday.

Seoul officials may see the measure as an inevitable response to China’s unilateral declaration on Nov. 23 of its air defense zone, which overlaps those of South Korea and Japan, and includes the airspace over a South Korean-controlled submerged rock. They say prior consultations have been made with neighboring powers. But unfavorable reactions from China, Japan and the U.S. may still test their capability to make a firm case for the measure.

South Korean officials seemed somewhat perplexed with China’s sudden move, which should make them recognize the complexity of striking a delicate strategic balance among neighboring powers. This task requires concrete measures crafted out in advance on the basis of a long-term and comprehensive review of how the regional situation will unfold.

It cannot be said that the national security team formed by President Park has acted in this manner. They appear to have relied on wishful thinking rather than having taken a hard look at regional security matters.

Their hope that China would respond considerately was shattered when Chinese military delegates refused to reconsider Beijing’s unilateral establishment of the air defense zone during talks with South Korean defense officials in Seoul last week.

They also seem to have missed the point in dealing with the issue of Japan exercising its right to collective self-defense. During his visit to Washington in October, a top South Korean security official was said to have focused on criticizing Tokyo’s move, which U.S. officials had already decided to back up to keep a rising China in check.

A hard sense of reality and a strategic adroitness are all the more required of Seoul’s national security team as the North Korean situation has become more volatile. Precautionary measures should be taken in close cooperation with all the regional powers against the possibility of Pyongyang returning to its old habit of committing provocative acts to cover up internal vulnerabilities.

In a fully conceived and well-measured way, Seoul needs to assume a more active role in resolving problems involving the North and lowering the possibility of regional confrontations.