Well, yeah, constitutionally speaking, Republic of Korea is the only rightful government with sovereignty over the whole Korean peninsula (and if you go across

Well, yeah, constitutionally speaking, Republic of Korea is the only rightful government with sovereignty over the whole Korean peninsula (and if you go across the border, you will here the same in reverse, except they recently decided to change their stance to "there are two countries and we're not related at all!"). But everyone understands that this is a legal fiction. Despite mutual hostility, the two Koreas are somewhat relaxed about interpretation: for example SK doesn't object to other nations establishing diplomatic relations with NK, and vice versa. Depending on who you ask, you'll hear different views on how to reconcile the law with reality, ranging from "there is only one rightful government, and a group of commie rebels we should destroy" to "we should accept that there are two different nations" to "South Korea is but a colony of American Imperialists!" But anyway, everyone accepts that practically there are two countries, so when we're talking about any contemporary matters, we're usually just talking about South Korea. (Unless we're specifically interested in North Korea.)