WASHINGTON (Kyodo) -- The U.S. government said Wednesday it has approved the sale to Japan of additional air-to-surface missiles and related equipment for an estimated cost of $39 million.

The Defense Security Cooperation Agency notified Congress of the plan concerning the extended-range standoff missiles, also known as JASSM-ER, earlier in the day.

In the face of rising security challenges posed by China and North Korea, Japan has been beefing up its defense capabilities. Such missiles are capable of targeting adversaries from outside their strike range.

In late 2022, Japan updated its key defense documents to acquire so-called counterstrike, or enemy base strike, capabilities in a major policy shift under the country's war-renouncing Constitution.

The approval came after the Japanese government asked to buy up to 16 of the missiles, according to the agency.

"This proposed sale will support the foreign policy goals and national security objectives of the United States by improving the security of a major ally that is a force for political stability and economic progress in the Indo-Pacific region," it said in a statement.

The missiles will be mounted on Japan's Air Self-Defense Force F-15 and other fighter jets.