N. Korea vows 'tit-for-tat' action against S. Korea-US military exercise

North Korea on Tuesday denounced South Korea's ongoing joint military drills with the United States and a separate exercise between the US and Japan, calling them "muscle flexing" by "enemy states."

In an English-language commentary carried by the Korean Central News Agency, the North warned that a "tit-for-tat principle based on strong power will be applied" in response to the military exercises.

"The present situation, in which the hostile forces get frantic in their military moves to infringe upon the security interests of the DPRK and undermine the regional strategic stability, highlights the validity and justness of the DPRK's indispensable self-defensive efforts to deter them," it said, referring to North Korea by its official name, the Democratic People's Republic of Korea.

The commentary came as South Korea launched the annual Hoguk field exercise involving US forces Monday, while Japan also kicked off large-scale military drills with the US, called "Keen Sword," the same day.

On the South Korea-US drills, Pyongyang slammed Seoul for not concealing the "aggressive and provocative nature" of the exercise, warning that escalating threats would require stronger deterrence.

"Bolstered deterrent is required to deal with ever-escalating threats, and repeated provocations are bound to meet with such prompt reaction as bolstering of stronger capabilities," the KCNA said.

"To cope with the security environment on the Korean peninsula that has been put in new danger by oft-repeated US-Japan-ROK military provocations, the DPRK will continue to remind them of its will to defend sovereignty through ceaseless upgrading, bolstering and responsible demonstration of its reliable war deterrent for self-defence," it added.

The Hoguk exercise is scheduled to run through Oct. 30. The US Forces Korea is also participating in the drills to enhance interoperability with South Korean troops, according to the Joint Chiefs of Staff.