The powerful sister of North Korean leader Kim Jong Un has warned the U.S. military that it will face a "very critical flight" if it repeats what she called acts of "illegal intrusion," state-run media reported Tuesday.

The statement by Kim Yo Jong, a senior official of the ruling Workers' Party, was released by the official Korean Central News Agency, which reported Monday that a strategic reconnaissance plane of the U.S. Air Force had violated the country's airspace off its coast.

Kim Yo Jong. (For editorial use only)(Yonhap/Kyodo)

Kim criticized South Korea for denying that the U.S. military has been violating North Korea's sovereignty by making such reconnaissance flights.

South Korea's military has called on North Korea not to escalate tensions by refraining from making threatening remarks regarding routine flights by U.S. aircraft under the Seoul-Washington alliance.

Lee Sung Jun, a spokesman of South Korea's Joint Chiefs of Staff, told reporters Tuesday that North Korea's latest claims were "not even worth a thought."

"As you well know, the exclusive economic zone is where there is freedom of navigation and overflight. We don't usually use such an expression like 'intrusion' even if there was a flight over it," Lee said, adding that North Korea seems to be constructing a rationale for provocative action.


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