Participating U.S. forces included the Arleigh-Burke-class guided-missile destroyer USS William P. Lawrence and a maritime patrol aircraft, according to South Korean naval officials. South Korea contributed roughly 10 aircraft and 10 warships, including the destroyer ROKS Yulgok Yi I.

The top military officers of South Korea and the US vowed to further strengthen the allies' trilateral security cooperation with Japan during their first video talks earlier this week, the

North Korean leader Kim Jong Un called for ‘all units in the entire military’ to bring about ‘a breakthrough in war preparation’, state media said.

North Korean leader Kim Jong-un has said that the most “crucial task” for the country’s armed forces is to make “full preparations for war”.

Japan has stepped up its air defences amid rising tensions in Asia after acquiring three advanced F-35 Lightning II aircraft from the United States. The fifth-generation fighter jets will be based at the Komatsu Air Base in Ishikawa, located on the country's west coast just off the Sea of Japan, also known as the East Sea.

North Korea is in its "strongest strategic position in decades," the U.S. Defense Intelligence Agency said in a new assessment.