North Korea on Tuesday denounced South Korea's ongoing joint military drills with the United States and a separate exercise between the U.S. and Japan, calling them "muscle flexing" by "enemy states." In an English-language commentary carried by the Korean Central News Agency (KCNA), 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 U.S. forces Monday, while Japan also kicked off large-scale military drills with the U.S., called "Keen Sword," the same day. On the South Korea-U.S. drills, Pyongyang slammed Seoul for not concealing the "aggressive