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.

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.

A blistering heat wave sweeping across the Korean Peninsula has forced the U.S. and South Korean militaries to postpone half of their field training drills this month, scaling back Ulchi Freedom Shield one of their largest annual joint exercises,