The North Korean military on Tuesday threatened to respond in a ruthless way to the large annual military maneuvers between South Korea and the United States, that began Monday, which Pyongyang considered "extremely dangerous reckless action."

The Pyongyang regime said it cannot avoid a "ruthless retaliation" because the allies have disregarded its warnings to make the right choice, warranting Pyongyang's merciless punishment, according to a statement released Tuesday by the North Korean KCNA news agency.

Amid one of the worst escalations in recent years between Pyongyang and Washington, South Korea and the US began Monday their annual Ulchi-Freedom Guardian military exercises, involving about 67,500 soldiers.

"The US should take the whole responsibility for catastrophic results from its reckless war game as it choose to make a military confrontation with us," added the text which was signed by North Korea's military representative stationed in the truce village of Panmunjom, on the border with South Korea.

The world's largest computerized simulated war drills, the Ulchi-Freedom Guardian military exercises will last until Aug. 31 and seek train the joint responses to a North's hypothetical invasion of the South.

Pyongyang, however, considers such drills as preparations to attack its territory and last year responded by launching a ballistic missile test from a submarine.

The exercise come shortly after the US and North Korea staged one of the worst rhetorical escalations in recent years.

In early August, North Korea first threatened to attack the US in retaliation for the new UN sanctions, imposed on the regime for its recent intercontinental ballistic missile launches, to which US President Donald Trump responded in an unusually belligerent tone.

Pyongyang subsequently unveiled a plan to bomb the vicinity of Guam Island, home to major US bases, although last week it tempered the tension, saying it would watch "a little more" for Washington's conduct before attacking.