South Korean and U.S. forces will begin their annual Ulchi Freedom Shield military exercises next week to strengthen readiness against North Korean threats.

The 11-day drills will involve about 18,000 South Korean troops and will include training based on lessons from recent conflicts.

U.S. officials said the exercises will account for North Korean soldiers’ recent combat experience from supporting Russia’s war in Ukraine.

The drills come days after North Korea resumed ballistic missile testing, which is prohibited under U.N. Security Council resolutions, the AP has reported.

North Korea has long condemned the exercises as preparations for an invasion, while South Korea and the U.S. maintain that the drills are defensive.