As expected, the decision to deploy a U.S. missile defense system in South Korea has many ramifications that pose hard challenges to the country -- specifically to President Park Geun-hye.

First of all, Park -- as the commander-in-chief -- needs to make sure the South Korean military prevents or deals properly with any provocations from North Korea, which is reacting fiercely to the planned deployment of the Terminal High Altitude Area Defense.

In its first reaction to the announcement, the North’s military threatened a direct strike, using phrases like “sea of flames” and “heaps of ashes.”

The statement released by the North Korean army’s artillery command said it would take “physical” actions against South Korea and the U.S. “from the moment” the location for the THAAD system is fixed. 

The statement, which came three days after the South Korea-U.S. announcement, also seemed geared toward keeping the Pyongyang government in tune with China and Russia, which have also been vehemently protesting the decision.

It went on to say that South Korea and the U.S. are building an “Asian version of NATO” and trying to “check big countries in Northeast Asia.”

It is obvious that North Korea is taking advantage of the THAAD issue to strengthen its solidarity with Russia and China. This may cause cracks in the current international sanctions against the North and embolden the North to make military provocations against the South. Park and her military generals must be prepared for this.

Another major challenge for Park is minimizing THAAD’s negative impacts on South Korea-China relations. China’s strong protests have largely been anticipated, but reactions from the Beijing government and some media do raise concerns.

It is not legitimate for China to blame only South Korea and the U.S. for the current situation, which was caused by North Korea’s pursuit of nuclear bombs and missiles.

Being the North’s former war ally and largest benefactor, China has done little to rein in the state, only calling for “calmness” whenever tension rises on the Korean Peninsula. Now is the time for the Beijing to stay calm and not damage relations with Seoul.

There are already news reports – including those by the state-controlled Chinese media – speculating or urging action against the South Korean government and businesses in retaliation for the planned THAAD deployment. 

This requires immediate attention from the two countries’ leaders and diplomats. It is hoped that the series of multilateral meetings later this month, including the Asia-Europe Meeting, ASEAN Regional Forum and the G20 summit, will help Park and Chinese leaders, including President Xi Jinping, tackle the problem in a mutually beneficial way.

On the domestic front, Park also faces the challenge of overcoming opposition to the deployment of the U.S. missile defense system.

Opposition parties and politicians are currently not united on the issue, with some expressing tacit approval and others even demanding parliamentary endorsement or a national referendum.

Protests by residents of the places where the THAAD battery might be positioned will not be easy to overcome either. The worse-case scenario would be a revival of the anti-American movement. There are also signs that liberals might use the issue to get ahead in the next presidential election.

All this gives Park no room for the negligence and blunders that have often been made since she became the chief executive.