Japan's top currency diplomat implies yen drama may not be over

Yen strengthens to 157.1 range against the dollar after Thursday night intervention

Japan’s vice finance minister on May 1 issued a warning against possible speculative currency trading. (Photo by Jo Ishibuchi)

TOKYO -- With the yen coming off a dramatic overnight gain against the dollar, Japan's vice finance minister for international affairs on Friday morning took an indirect path to warn against any speculative currency trading.