The deteriorating public sentiment following the ferry tragedy last month led President Park Geun-hye to dismiss her national security adviser and intelligence chief Thursday when she nominated a new prime minister.

Kim Jang-soo, head of the presidential national security office, had come under fire for disavowing responsibility for the handling of the disaster and National Intelligence Service Director Nam Jae-joon had been under pressure from the opposition to resign over a series of scandals.

Announcing their dismissal, a presidential spokesman said their successors would be appointed “soon.” Three hours after the announcement, North Korea fired two artillery shells near a South Korean warship on patrol near the disputed West Sea border. The South’s gun boat fired back several rounds into the northern waters, targeting a patrol ship located nearest to the border.

The latest provocation, which was later denied by Pyongyang, seemed deliberately timed to test the response from Seoul after the dismissal of the two key officials. With the post of national security adviser left vacant, a security ministers’ meeting was not held immediately. President Park convened the meeting the following day, in which the deputy national security adviser took the place of Kim.

This situation raised the need for Park to appoint a successor simultaneously if she dismisses her top aide on national security again. The president is also advised to take a more balanced approach to rebuilding her national security team, which has been swayed by figures with military backgrounds. Both Kim and Nam are retired four-star Army generals.

Seoul needs more flexible and strategic thinking to strike a delicate balance between the U.S. and China. This task is becoming more complicated as the two superpowers are strengthening their alliances with Japan and Russia, respectively, reducing South Korea’s room to maneuver between the two blocs, a situation reminiscent of the Cold War era.

A more sophisticated strategy is also needed to handle inter-Korean relations over the long term, as Pyongyang followed its latest provocative act with an announcement that it would participate in the 2014 Asian Games to be held in South Korea.