The guns fell silent in the Korean War seven decades ago, but the hostilities never truly ended. Today, North Korea’s secretive dictator oversees an isolated society and command economy, portraying himself as the benevolent protector of a nation under siege from hostile foreign powers. Its wealthy, democratic southern neighbor is an industrial and technological powerhouse that’s exporting its culture to the world, shielded from the nuclear-armed North by a defense treaty with the US. More than 1 million troops, and one of the heaviest concentrations of weapons anywhere, face off along a strip of no-man’s land that’s divided the two Koreas since 1953. North Korean leader Kim Jong Un has been raising the stakes by expanding his nuclear arsenal and threatening to unleash it on the US and its allies. Meanwhile, a postwar generation is dying without ever having fulfilled the dream of meeting their relatives living across the border. Korea was a single nation for centuries under the Goryeo and the Joseon dynasties, and through a period of Japanese colonial rule from 1910 to 1945. The Soviet Union joined with the US to expel the Japanese from the peninsula in the latter days of World War II. The victors divided the country, with Russia exerting its influence north of the 38th parallel — the line of latitude 38 degrees north of the equator — and the US doing the same in the south.

Full explainer : The uneasy truce between the nuclear-armed North and the US-allied South remains one of the most vexing security concerns for the world.