North Korea has threatened to sternly “punish” with ruthless attacks a joint South Korea-U.S. naval drill scheduled to open in the Yellow Sea on Sunday.

North Korea issued the threat on Friday via a Web site operated by the Committee for Peaceful Reunification of the Fatherland.

In a statement issued on the Web site "Uriminjok-kkiri", the North said that the U.S. has unveiled plans to hold a dozen joint naval drills before the end of the year. Pyongyang claimed that the drills are aimed at pushing forward efforts to invade the North.

Four ships and a patrol airplane from South Korea and three ships and a fast-attack submarine from the U.S. will take part in the upcoming drills.