The $550 billion investment that may determine the success or failure of the US-Japan trade agreement is still a mystery.

The United States and Japan reached what President Trump called the largest trade agreement in history this week, with Japan also pledging to establish a $550 billion fund for investment in the U.S. However, the details of how this fund will operate are unclear, fueling doubts about the feasibility of the agreement; the agreement will impose a 15% tariff on Japanese cars and other goods. While the start date and other key elements are still unknown, U.S. Treasury Secretary Steven Mnuchin warned this week that the U.S. will oversee implementation and if Trump is not satisfied, tariffs on Japan could be raised to 25%. The leaders of the two countries seem to be speaking different messages at times. The White House stated that the investment of over $550 billion will be led by the U.S., with Trump stating on social media that 90% will be "given" to the U.S. On the other hand, Japanese Prime Minister Shizo Abe has stated that Japan will provide up to $5.5 billion in investment, loans, and loan guarantees.