TOKYO, Aug 3 (Reuters): Japan and the United States conducted coordinated yen-buying intervention and will not hesitate to take further action, Japan's finance ministry said on Monday, confirming a rare bilateral action to halt the 's slide to fresh 40-year lows.

The move underscored both countries' resolve to prevent a selloff in the yen and Japanese government bonds (JGBs) from causing global spillovers, such as adding upward pressure on already rising U.S. Treasury yields, analysts said.

The joint intervention was the first since 2011's coordinated action to weaken the yen following the devastating earthquake in eastern Japan.

President Donald Trump said on Sunday the United States was helping Japan prop up the yen as a sign of friendship and to help the world economy.

Aside from helping Japan as a strategic ally in Asia, the intervention would help the United States address concerns over extraordinary weakness in the yen that offsets the boost from Trump's tariffs, analysts say.

In the statement, Japan's finance ministry said Friday's yen-buying intervention with the U.S. Treasury Department "countered excessive volatility and disorderly ⁠movements in the Japanese yen in recent months".

"We will not hesitate conducting further coordinated intervention," Finance Minister Satsuki Katayama told reporters on Monday.

The yen surged more than 1% to 155.20 per dollar after the announcement, its strongest since early May and well off the 40-year low near 164 hit last month, as traders remained on alert for more intervention.

Katayama declined to comment when reporters asked whether the authorities stepped in on Monday.

Photo from Reuters