SEOUL, South Korea (AFP) — North Korea fired an intermediate-range ballistic missile over Japan on Tuesday, prompting Tokyo to activate the country's missile alert system and order people to take shelter.

"North Korea appears to have launched a missile. Please evacuate into buildings or underground," the Japanese government said in an alert issued at 7:29 a.m.

Japanese Prime Minister Fumio Kishida told reporters that the launch was "an act of violence following recent repeated launches of ballistic missiles. We strongly condemn this."

South Korea's military said it had detected the launch of an IRBM, which flew around 4,500 kilometers at an altitude of about 970 kilometers and a speed of around Mach 17.

South Korea's President Yoon Suk-yeol called the launch a "provocation" that violated United Nations regulations.

Yoon "ordered a stern response and to take corresponding measures in cooperation with the United States and the international community," his office said in a statement.

North Korea was not responding to routine daily contact on the inter-Korean liaison line Tuesday, Seoul's unification ministry said.

Pyongyang's latest bout of intense weapons testing comes as Seoul, Tokyo and Washington ramp up joint military drills to counter growing threats from the North.

South Korea, Japan and the US staged anti-submarine drills Friday — the first in five years — just days after Washington and Seoul's navies conducted large-scale exercises in waters off the peninsula, involving a nuclear-powered US aircraft carrier.

Such drills infuriate North Korea, which sees them as rehearsals for an invasion.

The last time North Korea fired a missile over Japan was in 2017, at the height of a period of "fire and fury" when Pyongyang's leader Kim Jong Un traded insults with then-US president Donald Trump.