maybe they’re more interested in buying some US exports now?
That's the way I'm seeing it. Why should we get bent out of shape about North Korea walking over South Korea, when South Korea refuses to trade fairly with us? They enjoy annual $11B-14B trade surplus with the US, while we spend who knows how many billions each year keeping US troops on their border.
If they want to continue to enjoy the umbrella of US protection, it's time to start opening their markets, immediately. I'm no longer eager to borrow money from China to protect South Korea from North Korea. It's insanity.