North Korea vows response to US submarine visit to South Korea

The USS Vermont, a nuclear-powered and fast-attack submarine, enters a naval base in Busan, South Korea (Gang Sun-bae/Yonhap via AP)

The powerful sister of North Korean leader Kim Jong Un vowed on Tuesday to boost the country’s nuclear war capability and take other steps to protest against the recent arrival of a nuclear-powered US submarine in South Korea.

North Korea has repeatedly vowed to expand its nuclear arsenal, but the latest threat by Kim Yo Jong came after North Korea raised regional tensions by unveiling a uranium-enrichment facility and testing a new ballistic missile earlier this month.