Martial law is traditional South Korea governance.
The line dividing North and South Korea was created by US as it took it over from Japan after ww2, with puppet corrupt government installed.
The Korean war was instigated by US after national elections had North Korean as victor who threatened to unify and kick US out. Corrupt autocracy prevailed until 1980, and then the “democracy” that has followed since is/was an oligarchy of historically pro-Japanese family dynasty industrial champions.
Yet another sham the US calls a “democratic ally” for hegemonic legtimacy.