TOKYO--Japan's top currency official pledged to stay on guard against potential reaction in the foreign exchange market to President Trump's policies, which have already caused some swings in the yen ...

The Japanese currency similarly slumped to a 15-year low ... The yen had jumped briefly against the greenback in New York hours on Monday after striking the year-to-date low, which analysts ...

The yen slid the most among its major peers as traders in Tokyo returned from the holiday season and sold the currency. The Japanese currency weakened as much as 0.4% to 157.83 per dollar Monday ...