TOKYO, Aug 2 (Reuters) – Japanese Finance Minister Satsuki Katayama will announce on Monday that Tokyo and Washington took joint action ‌in the currency market to arrest the yen’s slide to ‌40-year lows, two Japanese government officials told Reuters.

Katayama is likely to stress the two countries’ ​determination to combat what they consider excessive yen declines, said the sources familiar with the matter, on condition of anonymity due to the sensitivity of the matter.

One source, asked if Katayama would announce “joint action”, said yes, ‌adding, “The operation is still ⁠ongoing.”

The Ministry of Finance could not immediately be reached for comment on Sunday. U.S. Treasury officials did not ⁠immediately respond to requests for comment.

The expected announcement follows what market sources say were rounds of yen-buying in the market by the Japanese and U.S. ​authorities, ​the first such joint intervention since ​2011, seeking to boost the ‌Japanese currency from its lowest levels against the dollar since 1986.

Japan’s government conducted yen-buying, dollar-selling intervention in New York hours on Thursday, a market source told Reuters. The move came hours before the Bank of Japan’s decision on Friday to keep monetary policy steady while signalling a ‌strong chance of an early interest rate ​hike.

Treasury Secretary Scott Bessent, who said ​last week the yen “seems very ​undervalued to me”, had a notepad at a Friday ‌cabinet meeting with the words “To Do”, ​followed by “Buy Japanese ​Yen (JPY) $5-10 bil”, a Reuters photo showed.

Also on Friday, the Treasury informed a number of banks that it might intervene in the ​yen market and that ‌they should “stand ready for future action,” a source familiar with ​the matter told Reuters.

(Reporting by Tamiyuki Kihara, Makiko Yamazaki and ​Leika Kihara; Editing by William Mallard)