Japan issued its strongest warning over sharp currency movements in weeks after the yen set a fresh 10-month low against the dollar overnight.

The nation’s top currency official said speculative moves could be seen in the foreign exchange market and warned that Tokyo was prepared to take action if needed.

“If these moves continue, the government will deal with them appropriately without ruling out any options,” said Masato Kanda, vice finance minister for international affairs.

The comments come after the yen weakened to 147.80 against the dollar, which strengthened against major peers amid a selloff in Treasuries. The yen edged higher after the remarks, rising 0.2% to around the 147.50 level.

Kanda said currencies should move stably in the market in a reflection of economic fundamentals. Officials are watching the market with a high sense of urgency, he added.

Japan’s currency officials have largely stayed quiet as the yen inched lower in recent days. They have repeatedly said that they are concerned about sharp movements in the yen not about specific levels against other currencies.

The nation last stepped into markets to prop up the yen in October.