The red of Korea is unquestionable. Whether it is the South Korean or the North Korean national team.
In this case, the one playing in the World Cup is the South Korean team. The Asian team that has participated the most times in the World Cup.
But why do we talk about two Koreas?
Well, it's because this peninsula, north of China, was occupied for a long time by the Empire of Japan, from 1910 to 1945. And the invaders committed all kinds of atrocities: killings, mass rapes, etc.
At the end of World War II, the Soviets liberated the entire north of the peninsula, and the Americans also hurried to occupy the south, anticipating what was to come: the Cold War.
A boundary was then established at the 38th parallel. In the north, a socialist republic, under the tutelage of the Soviet Union. In the south, a capitalist country, a satellite of the United States. The first time the Cold War heated up was during the Korean War, which lasted from 1950 to 1953 and left 2,500,000 dead. The two Koreas never signed a peace treaty, only an armistice, so technically they are still at war.