Japan may be the next target of U.S. President Donald Trump's trade war.

In a call to James Freeman, assistant editor of The Wall Street Journal's editorial page, Trump seemed to be still bothered by the terms of U.S. trade with Japan.

Freeman wrote that Trump described his closeness with Japanese Prime Minister Shinzo Abe, but added: "Of course that will end as soon as I tell them how much they have to pay." The writer said the president was "very stable but unfortunately also still very focused on eliminating trade deficits with America's trading partners."

China has been the main target of Trump's trade war in Asia, and the world is awaiting a third round of tariffs targeting $200 billion worth of Chinese products. The world's largest economy has already hit the second biggest with two sets of tariffs, both of which prompted Beijing to immediately counter.

The report made investors nervous about a potential new flash point in the trade war, causing the yen to rise against the dollar -- moving as high as 110.37 from 111.34 the previous evening.

Masayuki Yuda