North Korea launches a missile ahead of Vice President Harris's visit to the region.

According to South Korea's Joint Chiefs of Staff, the missile was fired by North Korea from the Taecheon region in North Pyongan province at 6:53 a.m. local time, travelling approximately 373 kilometers and reaching an altitude of around 38 miles.

South Korean authorities stated on Saturday that there were indications that North Korea was planning to test a submarine-launched missile, according to Yonhap news agency.

This year, North Korea has conducted a record number of missile tests as it builds its weapons program. The latest launch occurred as the nuclear-powered aircraft carrier USS Ronald Reagan landed in South Korea for joint military drills aimed at demonstrating the strength of the allies and acting as a deterrent to any nuclear threat.

A senior US administration source indicated ahead of Harris' journey to the area this week that any missile launch timed to coincide with her visit "would result in extra action by the US to emphasize our unwavering commitment to the security of the Republic of Korea and our Japanese friends."

The vice president is likely to discuss the escalating North Korean threat with her South Korean counterparts and express unity with Seoul.

"We've made clear how disturbed we've been by North Korean... provocations and disruptive conduct, and a nuclear test would undoubtedly fall into that category," an administration official said during a conference call with reporters.

South Korean President Yoon Suk-yeol, a conservative elected in May, has pledged to cooperate more closely with the US in response to North Korea's expanding nuclear and missile capabilities. This summer, the allies conducted their greatest field drills in five years.

Harris is scheduled to arrive in South Korea this week after attending the official funeral of assassinated former Japanese Prime Minister Shinzo Abe in Tokyo on Tuesday.

Following the missile launch on Sunday, Japanese Prime Minister Fumio Kishida gave instructions to "secure the safety of airplanes, warships, and other assets" and to take all precautionary measures.

North Korea usually reacts strongly to joint drills between South Korea and the US, labeling them "rehearsals for invasion." The allies claim the drills are defensive, but Pyongyang has exploited them to justify its nuclear development.

According to Soo Kim, a policy analyst at Rand Corp. in Washington, North Korean leader Kim Jong Un "does not want to be eclipsed geopolitically" by the return of the USS Ronald Reagan to South Korea and Harris' planned trip.

"With a spotlight on the US-South Korean relationship," she added, "it may have been essential for North Korea to fire a missile to reassert relevance and convey [Kim's] scorn for the US and South Korea."