The yen fell below Y155 to the dollar for the first time since July, raising the risk that Japan will enter the currency markets to try to slow the devaluation.

The yen fell 0.3% to 155.04 against the dollar after Donald Trump was re-elected as U.S. president.Soaring Treasury yields have put pressure on the yen, with two-year Treasury yields reaching their highest level since July.

The yen's decline is close to the level it saw when the Japanese authorities last intervened to support the country's currency, and Japan's top foreign exchange official warned of such a one-sided and sudden trend.A Bloomberg survey of 53 economists last month showed that the lowest forecast for the yen against the dollar that could trigger intervention was 150, with a median of 160.

Trump's expansionary and inflationary economic policies may weaken the Fed's willingness to lower interest rates.That could further weaken the yen as markets question the pace of further narrowing the interest rate gap between Japan and the United States.

The Japanese government has been vigilant about the timing of the next currency intervention.This year, Japan spent a record 9.8 trillion yen ($63 billion) on interventions in late April and early May, and another 5.5 trillion yen after reaching its weakest level since 1986 in early July.

The continued weakness of the yen may also prompt the Bank of Japan to consider raising interest rates earlier than expected.Bank of Japan Governor Kazuo Ueda admitted at a press conference in October that foreign exchange rates have been affecting Japan's price movements.