Update via Reuters: the president says he’ll abide by the parliament’s decision and revoke his declaration. Nobody started obeying it anyway - the military tried to do something because they had orders, but was not enthusiastic enough to achieve anything.

https://www.reuters.com/world/asia-pacific/south-korea-president-yoon-declares-martial-law-2024-12-03/

Some analysis via the Guardian:

https://www.theguardian.com/world/2024/dec/03/declaration-of-martial-law-awakens-ghosts-south-koreans-thought-were-laid-to-rest

Yoon’s declaration of martial law appears to have been a desperate gamble in the face of rock-bottom public popularity – with positive ratings barely over 10% – in the midst of a doctors’ strike and staunch political opposition, increasingly including his own People Power party, whose leader, Han Dong-hoon, said the declaration of martial law was a “wrong move”.

Yoon may have thought that his nostalgia for authoritarianism would resonate with at least some of the South Korean political spectrum, but the unanimous vote in the national assembly to overturn his declaration, including by his own party, suggests he miscalculated.