Three U.S. officials said preliminary assessments suggested the missile was fired by Ukrainian forces at an incoming Russian missile.
The North’s announcement underscored leader Kim Jong Un’s determination not to back down in the face of his rivals’ push to expand their military exercises.
North Korea’s Foreign Ministry late Friday described the country’s military actions this week as an appropriate response to the exercise.
The longer-range missile was fired on a high angle, apparently to avoid reaching the territory of neighbours, reaching a maximum altitude of 1,920kms and travelling around 760kms.
North Korea fired about a dozen missiles Wednesday, at least one of them in its direction and landing near the rivals’ tense sea border.
The launches came hours after North Korea threatened to use nuclear weapons to get the U.S. and South Korea to 'pay the most horrible price in history'.
One short range ballistic missile crossed the Northern Limit Line, the de facto maritime border between the two countries.
Since late September, North Korea has launched a barrage of missiles toward the sea in what it called simulated tests of tactical nuclear weapons systems designed to hit South Korean and US targets.
Beside the usual sirens, a new type of loud alarm that blared automatically from mobile phones jolted Kyiv residents early Tuesday.
UN chief Antonio Guterres condemned the strikes as "another unacceptable escalation" while French leader Emmanuel Macron called them "a profound change in the nature of this war."
The country revised its nuclear laws last month to allow pre-emptive strikes, with Kim declaring North Korea an "irreversible" nuclear power.
"While strengthening our monitoring and vigilance, our military is maintaining a full readiness posture in close cooperation with the United States," the joint chiefs of staff said, Yonhap reported.
Some experts say North Korean leader Kim Jong Un is determined to expand his nuclear arsenal in defiance of international sanctions.
US and South Korean officials also say North Korea is possibly gearing up for its first nuclear test since 2017.
Schools in the Kyiv and Lviv regions were among those welcoming students back to classrooms Thursday, including more than 7,300 displaced students forced to flee their hometowns.
Russia's Defense Ministry said three MiG-31 fighters with Kinzhal hypersonic missiles arrived at Chkalovsk airbase in the Baltic Sea enclave as part of "additional measures of strategic deterrence.
Washington and Seoul officials have also warned that the isolated regime is preparing to carry out what would be its seventh nuclear test.
Guterres, who arrived in South Korea on Thursday, later met with South Korean Foreign Minster Park Jin for discussions that were expected to be centred around the North Korean nuclear threat.
Taiwan's military did not confirm the precise location of where the missiles landed or whether they flew over the island.
Iran’s mission to the United Nations did not respond to a request for comment.