South Korea has been trying to tell the US that they can't make a similar arrangement to that of Japan's $550 billion investment deal. And that is largely due to the potential impact on South Korea's foreign exchange market. The country's presidential chief of staff for policy, Kim Yong-beom, is out saying that:
"We are making the US side understand that the critical issue is how to secure and operate $350 billion in the foreign exchange market. South Korea struggles to secure more than $20 billion to $30 billion annually. Fundamentally, we are urging the US to help resolve concerns about the potential shock to the foreign exchange market... the $350 billion fund poses a massive short-term shock to our entire economy."
And that is what is leading to a delay in negotiations, as they are trying to sort out how to accommodate this matter.