The Article 4 [Unification, Peace]
The Republic of Korea shall seek unification and shall formulate and carry out a policy of peaceful unification based on the principles of freedom and democracy.
But are the South Korean people and their government really abiding to this law?
Then what problems are hindering North and South unification?
First of all, it seems like many people are not aware of this fact, but North and South Korea are technically still at war. The North and the South only signed a ceasefire agreement. Therefore, North and South have always and still maintain very hostile to each other.
Secondly, the North and the South have huge ideology difference. The political system of the North is essentially totalitarian and communist (although it is slowly turning more capitalistic), while the South maintains a strictly democratic system.
Thirdly, the North and the South can not find an agreement point if they were to unify. The South and the world insist that the unified Korea be a democratic nation, while the North do not want to concede its communist and totalitarian system. Therefore, most experts agree that an unified Korea would not be possible unless the Kim dynasty come to an demise
Fourthly, a tremendous cost follows unification. South Korean learned an important lesson from the German unification. In 1990, West Germany had about 4 times more population than the East Germany and approximately twice the GDP per capita. The German unification cost more than 2 trillion dollars, which all came from the pocket of West Germans. The cost of leveling the eastern economy and reconstruction heavily burdened the middle class in West Germany, putting Germany into economic recession. Situation is worse in Korea. The North has $1,800 GDP per capita while the South has $26,000, which is approximately 14 times the difference (significantly more than Germany in 1990). South Korea is already experiencing serious economic instability, and many simply say that both North and South go bankrupt if unification happens without some sort of economic leveling.
Lastly, the surrounding nations do not welcome Korean unification. From more than 60 years of hostility, both North and the South developed significant military power. Both has the technology to create nuclear weapons and both has large army, airforce and navy with brand-new weapons. If two nations unify, the unified Korea would own a formidable military force that can pose threat to nearby nations, especially to China and Japan. (China, Korea and Japan have a very long history of fighting one another)