SEOUL - The Democratic People's Republic of Korea (DPRK) armed forces are "strictly watching the frequent appearance of the US strategic means on the Korean Peninsula and are ready for using any means to defend the security and interests of the state and regional peace," a spokesperson for the DPRK's Defense Ministry was quoted as saying on Tuesday by the official Korean Central News Agency.

USS Alexandria, a Los Angeles-class nuclear-powered submarine, arrived at the naval base in Busan on Monday "under the pretext of the rest of the crew and replenishment of munitions," the spokesperson said, noting that this is the first overt emergence of a US nuclear submarine in the Korean Peninsula this year.

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The move "is an undeniable threat to the security environment of the DPRK and an unstable factor further escalating the military tension in the region," the spokesperson said. "We express grave concern over the US dangerous hostile military act that can lead the acute military confrontation in the region around the Korean Peninsula to an actual armed force conflict." The DPRK will "make clearer our choice of action and mode of counteraction against our rivals."

The spokesperson said the United States "is openly ignoring the security concern of the DPRK," and warned that the US should stop provocations.