A Peninsula Divided

When Japan surrendered in August 1945, the Korean peninsula — a single nation with a 5,000-year history — was hastily divided along the 38th parallel into Soviet and American occupation zones.

The division was intended as a temporary administrative arrangement, but it quickly hardened into something permanent as Cold War tensions transformed every corner of the globe into a battleground of ideologies.

In the north, the Soviet Union installed Kim Il-sung, a former guerrilla fighter who had spent years in the USSR, as head of a communist state modeled on Stalin's design. In the south, the United States backed Syngman Rhee, a fiercely anti-communist autocrat who had spent decades in exile lobbying for Korean independence.

Both Korean leaders were nationalists who dreamed of reunifying the peninsula — but under their own system. The years between 1945 and 1950 were marked by constant skirmishing along the parallel, political repression on both sides, and competing claims to legitimacy.

The Soviet Union provided Kim's North Korean People's Army with tanks, artillery, and modern weapons. American planners, still demobilizing after World War II and distracted by crises in Europe, gave the South Korean military only enough arms to maintain internal order — no tanks, no combat aircraft.

In January 1950, Secretary of State Dean Acheson, in a speech defining America's Pacific defense perimeter, appeared to exclude South Korea — an omission that Kim and Stalin interpreted as a green light.

Stalin's approval was crucial. Throughout early 1950, Kim lobbied Moscow for permission to launch the invasion he had long planned.

Stalin calculated that a quick North Korean victory was achievable before the United States could respond, and that even if America did intervene, the conflict would tie down US resources without risking direct Soviet-American confrontation. He approved the plan in April 1950, promising military advisors, equipment, and air cover.

Mao Zedong's newly victorious China also gave its blessing, though with private reservations about provoking American intervention near Chinese borders.

On June 25, 1950, after weeks of false reports of South Korean provocations, 135,000 North Korean troops with 150 T-34 tanks crossed the 38th parallel in a crushing dawn offensive. The surprised ROK Army, outgunned and poorly positioned, disintegrated. Seoul fell in three days.

President Truman, meeting urgently with his advisors, concluded that the invasion was a Soviet-backed test of American resolve that could not be allowed to succeed.

He committed US forces immediately and secured a UN Security Council resolution authorizing military action — possible only because the Soviet Union was boycotting the Council over Taiwan's seat. The Cold War had turned hot on the Korean peninsula.