Last week, the three countries held a three-day joint exercise, dubbed "Freedom Edge", featuring fighter jets and marine patrol aircraft as well as the US nuclear-powered aircraft carrier, USS George Washington, Reuters reported.
"We strongly warn the US and its followers hostile towards the DPRK to immediately stop the hostile acts of further causing provocation and instability that can drive the military confrontation in the Korean peninsula and its vicinity into a real armed conflict," the North's defense ministry said, using the country's official name.
The military would keep all options available and take immediate actions if needed to preemptively control risk, while closely watching military activity by the US and its allies, it said in a statement carried by state media KCNA.
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