The US has 73 bases in South Korea.
The US has 28,000+ military personnel occupying the country.
South Korea has no jurisdiction to charge any of these soldiers, if they commit a crime in their country.
South Korean military personnel are required to answer to US generals as a higher authority than their own.

We could also spend a while digging into the political and economic control the US exercises over SK, but a literal military occupation should suffice.

[–] anachronist@midwest.social 3 points 1 week ago

South Korean military personnel are required to answer to US generals as a higher authority than their own.

I've actually heard that the SK soldiers attached to the US military are mostly failsons of powerful people who pull strings to get them put in US formations for their mandatory service, because it's considered a cake-walk compared to the SK military.