Japan is expected to announce that Tokyo and Washington acted together in the currency market to support the yen, according to a report. The move is tied to efforts to halt the Japanese currency’s sharp decline after it fell to its weakest level in roughly 40 years.

The report says Japanese Finance Minister Satsuki Katayama plans to disclose the cooperation on Monday. People familiar with the matter reportedly indicated that Japan and the United States were involved in yen-buying action aimed at slowing the currency’s fall.

A joint step by Tokyo and Washington would stand out because currency intervention is closely watched by investors and can influence broader market expectations. It also highlights the pressure Japanese authorities have faced as yen weakness raises concerns about import costs and financial stability.

Markets will be looking for any official details on the scale, timing and purpose of the action once the announcement is made. For now, the reported cooperation suggests Japan sought international backing as it tried to steady the yen during a period of intense currency volatility.