Updated

North Korea's military unleashed its standard fiery threats to greet the start of annual U.S.-South Korean military drills that the North claims are an invasion rehearsal.

The North Korean rhetoric Tuesday came as top U.S. generals, including Adm. Harry Harris, the commander of U.S. forces in the Pacific, visited South Korea.

The U.S. generals were to travel to the site of a contentious U.S. missile-defense system in South Korea later Tuesday.

The North's military says it will launch an unspecified "merciless retaliation and unsparing punishment" on the United States over the Ulchi Freedom Guardian drills that began Monday.

North Korea has previously issued similar warlike rhetoric whenever U.S. and South Korean troops conducted major joint exercises.

An unprompted direct attack is extremely unlikely because the United States vastly outguns Pyongyang.