F-35B Lightning II stealth fighters pack the USS America's flight deck in the Coral Sea, July 31, 2023. (Kelly Agee/Stars and Stripes)

CAMP HUMPHREYS, South Korea — U.S. and South Korean troops kicked off a semiannual large-scale exercise Monday after the presidents of both countries agreed to expand their alliance during a trilateral summit with Japan.

Ulchi Freedom Shield, an 11-day exercise consisting of around 30 separate drills, has been described by U.S. Forces Korea and South Korea’s Ministry of National Defense as a routine, defensive exercise on land and in the air and sea.

One of the exercise’s key points is “to counter the advancing threats from North Korea,” South Korean Joint Chiefs of Staff spokesman army Col. Lee Sung-jun told reporters during a news briefing on Aug. 14.

Details, such as the number of troops involved, had not been disclosed by the ministry as of Monday. USFK, which commands roughly 28,500 troops on the peninsula, regularly declines to provide specifics about their large-scale exercises, citing operational security concerns.

The training began three days after President Joe Biden, South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida met at Camp David, the presidential retreat in Maryland. The leaders reaffirmed their security partnership and said they remained committed “to the complete denuclearization of [North Korea],” according to a joint statement.

“We remain committed to dialogue with [North Korea] with no preconditions,” the statement said.

North Korean leader Kim Jong Un directed the firing of strategic cruise missiles from a warship at a simulated target, according to a report from the state-run Korean Central News Agency on Monday. The report did not mention the date of the missile launch.

South Korea’s Joint Chiefs of Staff said it tracked the missiles in real time and described KCNA’s description of the launches as “exaggerated” without providing additional details, according to a message to reporters Monday.

Yoon presided over a National Security Council meeting Monday and highlighted the importance of the country’s military exercise with the U.S.

Peace is protected only by “overwhelming power, rather than one side begging or by one side’s goodwill,” Yoon said at the meeting, according to a news release from the presidential office.

North Korea has fired 17 ballistic missiles in 12 separate days of testing so far this year. It last launched two short-range ballistic missiles that flew roughly 340 miles before splashing down in the Sea of Japan, or East Sea, on July 19.