The "Freedom Edge" exercise is a response to what the South Korean military said were threats from North Korea, which recently conducted an intercontinental ballistic missile test, drawing condemnation from Seoul, Tokyo and Washington, Reuters reported.
It also comes as the US State Department said North Korean troops have started engaging in combat operations in Russia's war with Ukraine.
The exercise will include South Korean and Japanese fighter jets and maritime patrol aircraft, as well as the USS George Washington, Seoul's Joint Chiefs of Staff (JCS) said in a statement.
The trilateral exercise follows a first round held earlier this year after the leaders of the three countries agreed at a summit in 2023 to hold annual training drills.
Pyongyang has long condemned joint drills between South Korea and the United States, calling them a rehearsal for invasion.
The trilateral exercise will also include maritime missile defense training and cyber defense training, according to the JCS.
In a statement on Tuesday, the US Air Force said it would retire its A-10 Thunderbolt II aircraft in key regions including South Korea in the fiscal year 2025 as part of its modernization strategy.
The aircraft, nicknamed "The Warthog", was developed for the US Air Force by the Fairchild Republic Company, which is now part of Northrop Grumman, according to the US defense company's website.