Martial law lasted only a few hours, but the country's politics, diplomacy and financial markets have been shaken for weeks. The decree also exposed South Korea's deeply polarized society.

The spectacle at the compound follows Yoon’s astonishing decision last month to impose martial law during a seemingly routine impasse with the opposition, which dominates the National Assembly.

The spectacle followed Yoon’s astonishing decision last month to impose martial law during a seemingly routine impasse with the opposition, which dominates parliament. Here’s a closer view of ...