Treasury Secretary Scott Bessent said Tuesday that the U.S. joined Japan's effort to strengthen the yen because the currency's weakness risked destabilizing markets across Asia. "A stable yen is not only important for the U.S., but very important for the entire region," Bessent said on CNBC's "Squawk Box."

Bessent said a sharply weaker yen could pressure other countries to devalue their currencies, pointing to volatility in the South Korean won and concerns that China's yuan is undervalued. Given the trade flows, given the size of the economy, given their contribution to the global savings market, [it is] very important to have a stable yen," Bessent said. "The Japanese government understands that, and we are proud to stand with them in implementing their policies and help them stabilize the region."

The coordinated intervention is a rare U.S. effort to support another major currency and underscored Washington's concern that prolonged yen weakness could fuel inflation in Japan, pressure other Asian currencies and destabilize global markets. The Treasury Department sold euros from U.S. reserves and used the proceeds to buy yen as part of the coordinated operation.

Bessent cautioned that intervention alone would not determine the currency's direction. "You can give market signals with intervention, but it's policy that turns it," he said, adding that the U.S. participated because it was optimistic about Japan's policy path.