North Korea raises spectre of nuclear strike as US carrier arrives in South

The USS Ronald Reagan is escorted arrived in Busan, South Korea, on Thursday (Kang Duck-chul/Yonhap via AP)

North Korea has lashed out at the arrival of a US aircraft carrier battle group in South Korea, calling it a provocation and again raising the spectre of using nuclear weapons to defend itself.

Emboldened by its advancing nuclear arsenal, North Korea has increasingly issued threats to use such weapons pre-emptively.