North Korea fired an unspecified ballistic missile toward the East Sea on Thursday morning local time, just two days after Pyongyang sent an intermediate-range ballistic missile flying over Japan, South Korea’s Joint Chiefs of Staff said. 

About 40 missiles have been launched by North Korea this year, including six in the past two weeks, but Tuesday's test marked the first time in five years that the country has sent a missile over Japan. 

The U.S. and South Korea staged joint drills on Wednesday in response, with the USS Ronald Reagan moving into waters east of South Korea.

North Korea

A TV screen showing a news program reporting about North Korea's missile launch with a file image is seen at the Seoul Railway Station in Seoul, South Korea, on Tuesday. (AP Photo/Lee Jin-man)

One of South Korea's ballistic missiles, a Hyumoo-2, caught fire and crashed shortly after taking off on Wednesday, prompting criticism from local politicians in the coastal Gangneung area. 

NORTH KOREA THREATENS NUCLEAR ACTION IF KIM JONG UN ASSASSINATED: REPORT

The U.S. and allies called a United Nations Security Council on Wednesday amid the escalating tensions. 

"[North Korea] has enjoyed blanket protection from two members of this council," U.S. Ambassador to the United Nations Linda Thomas-Greenfield said, referring to China and Russia. "In short, two permanent members of the Security Council have enabled Kim Jong Un."

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Vice President Kamala Harris visited South Korea in late September and hailed America's "alliance with the Republic of North Korea" in a gaffe. She apparently intended to refer to the Republic of Korea, which is South Korea's official name. 

Fox News' Jennifer Griffin and Reuters contributed to this report.