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 that the U.S. move highlights the North's urgency to bolstering its nuclear forces.

The Carl Vinson Carrier Strike Group arrived in South Korea only days after Pyongyang carried out its fourth missile test this year.

USS Carl Vinson (CVN-70) pulled in to Busan Naval Base, South Korea on Sunday for a scheduled port visit, marking the first visit of a U.S. carrier to a foreign port during the second Trump administration.