Et tu, Brute?
If you've been keeping up with the news you would know that Iran told US either remove all sanctions in one go or there's nothing further to talk about.
Before US could say one way or the other (let's be serious here, it will be a no) South Korea does this.
Of course once South Korea returns Irans money they're not going to come home empty handed, they're going to make some sort of deal with Iran isn't it. And given Iran recently signed that 400 billion dollar deal with China for 25 years...
Consider what else happened recently:
You can see who's team South Korea is not on.