President Donald Trump’s demand that Seoul hand over $350 billion in cash could devastate South Korea’s financial markets and economy. In July, Korea agreed to invest $350 billion in the U.S., in exchange for Washington setting a 15% tariff rate. Korea has also pointed to major differences with Japan and why the terms of Tokyo’s $550 billion investment pledge shouldn’t be applied in the same way. For instance, Japan has more than triple Korea’s currency reserves at $1.3 trillion. The yen is also a much more international currency, accounting for 17% global market share versus just 2% for the won.