The White House has revealed that US Vice President Kamala Harris will inspect the demilitarized zone between North and South Korea on Thursday.

Harris arrived in Tokyo on Monday to attend Tuesday's state funeral of former Japanese Prime Minister Abe Shinzo. She is scheduled to visit South Korea on Thursday.

A White House official said on Tuesday her visit will underscore the strength of the US-South Korea alliance and show Washington's commitment to the South's security in the face of any threats posed by North Korea.

North Korea has repeatedly fired missiles this year, with unprecedentedly short intervals between launches.

This month, the country made clear it plans to push forward its nuclear development program.

Observers say Harris's visit to the demilitarized zone aims to curb Pyongyang's ambitions.