N. Korea fires missile ahead of regional visit by Vice President Harris

South Korean officials on Saturday said there were signs that North Korea was preparing to test a submarine-fired missile, Yonhap news agency reported.

North Korea has tested an unprecedented number of missiles this year as it expands its weapons program. The latest launch came as the nuclear-powered aircraft carrier USS Ronald Reagan arrived in South Korea for joint military exercises designed to showcase the allies’ strength and serve as a deterrent to any nuclear threat.

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Speaking ahead of Harris’s visit to the region this week, a senior U.S. administration official said any missile test timed to coincide with her trip “would result in additional action by the United States to demonstrate our ironclad commitment to the security of the Republic of Korea and to our Japanese allies.”

The vice president is expected to discuss with her South Korean counterparts the growing North Korean threat and demonstrate solidarity with Seoul.

“We’ve made clear how concerned we’ve been by North Korean … provocations and destabilizing behavior, and a nuclear test would certainly be in that category,” said the administration official, speaking on a call with reporters.

South Korean President Yoon Suk-yeol, a conservative who took office in May, vowed to work more closely with the United States in response to North Korea’s growing nuclear and missile capacity. The allies conducted their largest field exercises in five years this summer.

Harris is due to arrive in South Korea this week after attending the state funeral Tuesday of slain former Japanese prime minister Shinzo Abe in Tokyo.

Japanese Prime Minister Fumio Kishida issued instructions after the missile launch on Sunday to “ensure the safety of aircraft, vessels, and other assets” and to take all precautionary measures.

North Korea typically reacts angrily to the joint drills between South Korea and the United States, calling them “rehearsals for invasion.” The allies say the drills are defensive in nature, while Pyongyang has used them to justify its weapons development.

The USS Ronald Reagan’s return to South Korea and Harris’s upcoming trip have put Pyongyang on alert, said Soo Kim, a policy analyst at Rand Corp. in Washington, because North Korean leader Kim Jong Un “does not want to be overshadowed geopolitically.”

“With a spotlight being shone upon the U.S.-South Korea alliance,” she said, North Korea may have perceived it to be necessary “to fire a missile to reassert relevance and express [Kim’s] disdain toward the U.S. and South Korea.”

38 North, a website devoted to North Korean analysis, said Wednesday that images from a major shipyard in the North suggested that preparations were being made for the launch of a submarine potentially capable of firing ballistic missiles.