South Korea and the U.S. have canceled a massive joint aerial drill for the second time running this year.

The exercise, dubbed "Vigilant Ace," used be staged every December, and the last one in 2017, when the North Korean nuclear crisis reached boiling point, involved a record 230 warplanes.

Instead, the South Korean Air Force and the U.S. Forces Korea will conduct their own aerial drills separately as they did last year, a Defense Ministry spokesman here said Sunday.

