The powerful sister of North Korean leader Kim Jong-un on Tuesday warned of a stepped-up action against the arrival of a U.S. aircraft carrier in South Korea, claiming the U.S. move justifies the North bolstering its nuclear forces.

The U.S. aircraft carrier USS Carl Vinson arrived at the southern port city of Busan in South Korea on Sunday as a show of force against North Korea, South Korea's navy said. It is the first U.S. aircraft carrier to dock at a South Korean port since U.

North Korea has slammed the United States for "political and military provocations" over the visit of a US Navy aircraft carrier to the South Korean port of Busan. The USS Carl Vinson, the flagship of a carrier strike group,

The presence of a U.S. aircraft carrier in South Korea this week highlights the strengthening bilateral alliance, a U.S. admiral said Monday, a day after its arrival in the southeastern city of Busan.

The U.S. aircraft carrier USS Carl Vinson arrived at the southern city of Busan in South Korea on Sunday as a show of force, South Korea's navy said. The visit was part of the "ironclad" commitment of the United States to extended deterrence and to show readiness by the military alliance between Seoul and Washington against North Korea,