South Korea and the United States will conduct major joint military drills starting on August 18, officials said, although they will delay parts of the annual exercises that have been a source of tension with North Korea to later in the year.

SEOUL--South Korea and the United States will launch their annual large-scale military exercise this month to bolster readiness against North Korean threats, the allies said Thursday, in a move likely to irritate Pyongyang amid a prolonged stalemate in diplomacy.