North Korea vows to ‘step-up’ action against US as aircraft carrier arrives in South

The powerful sister of North Korean leader Kim Jong Un warned on Tuesday of a “stepped-up action” against the U.S. as one of its aircraft carriers arrived in South Korea, saying the “hostile” U.S. policy justified the bolstering of the North’s nuclear forces. The USS Carl Vinson, a Nimitz-class U.S. aircraft carrier, arrived at the southeastern city of Busan on Sunday, South Korea’s navy said,