Why are there two Koreas?

Thirty five years under Japanese rule

Korea existed as a single kingdom for centuries before Japan formally annexed it in 1910, ending the Joseon dynasty and beginning 35 years of colonial rule. Japanese administrators suppressed Korean language education and directed Korean rice, minerals, and labor toward Japan's own economy, a policy that intensified after Japan invaded China in 1937. The occupation ended abruptly with Japan's surrender in August 1945, but no independent Korean government was waiting to take its place; the peninsula's political future was decided almost entirely by outside powers, in a matter of days.

A line drawn in a hurry: the 38th parallel, August 1945

On the night of 10 to 11 August 1945, with Japan's surrender imminent and Soviet troops already advancing into Korea from the north, two US Army colonels, Dean Rusk and Charles Bonesteel, were given about thirty minutes to recommend a line dividing the peninsula into Soviet and American occupation zones. Working from a small National Geographic wall map, with no Korean consulted, they chose the 38th parallel because it split Korea roughly in half while keeping the capital, Seoul, inside the American zone. The Soviet Union accepted the proposal on 16 August, the day after Japan agreed to surrender; American troops did not land until 8 September, nearly a month after Soviet forces had already moved into the north. Rusk later admitted the line "made no sense economically or geographically." It was chosen for speed, not for any Korean reason, and both occupying powers treated it as a temporary convenience rather than a future border.

Two occupation zones become two governments

What began as a joint trusteeship broke down as Cold War distrust between Washington and Moscow deepened. Each side built a government in its own zone rather than negotiating a single one for the whole peninsula. In the south, the United States backed elections that brought Syngman Rhee to power, and the Republic of Korea (ROK) was formally established on 15 August 1948. In the north, the Soviet Union installed a government under Kim Il Sung, and the Democratic People's Republic of Korea (DPRK) was proclaimed on 9 September 1948. Both governments claimed to be the legitimate authority over the entire peninsula, a claim neither has formally dropped since. That December the United Nations General Assembly declared the Republic of Korea the only lawful government of its kind in Korea, while describing its effective control as covering the part of the peninsula where UN observers had been able to watch the elections, a decision the DPRK has never accepted.

The Korean War, explained

Believing the United States did not consider South Korea vital to its defense of East Asia, North Korean forces crossed the 38th parallel on 25 June 1950 and nearly overran the entire peninsula within weeks. A UN Command led by the United States pushed back and, after China entered on the North's side that autumn, the front stabilized close to where it had started. Two more years of largely static, costly fighting followed before military delegations signed the Korean Armistice Agreement at Panmunjom on 27 July 1953, ending active combat. No South Korean official signed it, and no peace treaty has ever followed, so the two Koreas remain, in a strict legal sense, still at war. The armistice created the Demilitarized Zone, a buffer roughly 2.5 miles wide straddling a new military line close to the original 38th parallel, and that line, not the 1945 one, is what divides the peninsula today.

North vs South Korea: the history since 1953

The two states diverged sharply after the war. South Korea moved from military rule through decades of rapid industrialization into a democracy and one of the world's larger economies, while North Korea built a centrally planned, heavily militarized state around the Kim family and, after Soviet aid collapsed in the 1990s, suffered a famine that killed hundreds of thousands of people. The gap shows up starkly in basic figures, though North Korea reports little economic data internationally, so its numbers are estimates and some, like GDP, are unavailable from the World Bank.

Figures from the same World Bank backed comparison dataset that powers the country comparison tool, so the numbers here and there cannot disagree. North Korea does not publish GDP data the World Bank can report, which is itself part of the story: the country that would let you measure the gap most precisely is the one that will not.

The clearest attempt to close that gap politically came in 2018, when South Korean President Moon Jae-in and North Korean leader Kim Jong Un held three summits, including one at the DMZ village of Panmunjom in April, and Kim held a separate summit with US President Donald Trump in Singapore in June. Those meetings produced joint declarations on denuclearization and peace but no lasting agreement, and the diplomatic opening had mostly closed again by the early 2020s.

Where relations stand in September 2026

As of September 2026, the diplomatic distance has widened rather than narrowed. North Korea revised its constitution in March 2026, and when the text became public in May it had dropped the old references to reunification and to a single Korean nation and added a clause defining the country's territory as ending at the line with South Korea. The revised text stops short of naming the South a hostile state in law, although North Korean state media has described it in those terms. Pyongyang has also shifted South Korea policy out of the ruling party body that long handled inter-Korean contact and into its Foreign Ministry, treating Seoul as a foreign capital rather than an internal matter. South Korea's government under President Lee Jae-myung has pushed for renewed dialogue, but Pyongyang has continued missile tests and rejected claims of any meaningful improvement. On 7 September 2026, North Korea and Russia opened their first road bridge across the Tumen River, a small but telling sign of where Pyongyang's diplomatic energy is currently directed instead.

Quick facts

• Japan ruled Korea as a colony from 1910 to 1945.
• The 38th parallel was chosen by two US officers, Dean Rusk and Charles Bonesteel, in about thirty minutes on 10 to 11 August 1945.
• South Korea (15 August 1948) and North Korea (9 September 1948) were founded within weeks of each other.
• The Korean War, 25 June 1950 to the 27 July 1953 armistice, ended in a ceasefire, not a peace treaty.

Common questions

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