A look at North Korean missile tests that crossed over Japan

— -- The North Korean missile launched on Monday proved unlike any rocket test seen in years because of its unusual trajectory over Japan, crashing down 500 nautical miles east of Hokkaido in the Pacific Ocean.

Despite North Korea testing numerous ballistic missiles in 2017, the regime has not launched a missile over Japan since 2009. Monday's event triggered sirens and text alerts as a warning to citizens by the Japanese government. North Korean missiles typically land in the Sea of Japan, shy of Japan's west coast.

A U.S. official told ABC News that Monday's test was assessed to be an intermediate-range ballistic missile -- a single-stage KN-17, referred to by North Korea as a Hwasong 12. It flew 1,667 miles horizontally to the east, reaching a maximum altitude of 310 miles -- far less than the height of last month's ICBM tests.

The missile broke up toward the end of its flight, the official said, but it's not assessed that the breakup was a test of a re-entry vehicle, which would be needed for North Korea to successfully launch a nuclear weapon.

Below, ABC News looks back at previous North Korean missile tests that crossed over -- or came close to -- Japan.

September 1998

Sept. 1, 1998, was the first time North Korea launched a missile over Japan.

The first part of the two-stage rocket, called the "Taepodong-1," was determined to have fallen into the Sea of Japan before the second stage flew over Japan and into the Pacific Ocean.

According to The New York Times, military officials believed the launch could have been tied to a North Korean holiday on Sept. 9, which celebrates the country's founding.

April 2009

In April 2009, North Korea launched another missile over Japan -- one the country said was carrying a satellite into space. But, unlike in 1998, the country issued a warning that the launch was going to take place.

"North Korea issued maritime and airspace notices about the trajectory of the launch and 'splash down' zones for stages of the rockets," said Kelsey Davenport, director of nonproliferation policy at the Arms Control Association.

Davenport told ABC News these notices specify a window during which a launch may occur, but not exact times and dates.

Though North Korea called the launch a success, the U.S. assessed that the satellite never entered into orbit.

December 2012 and February 2016

In December 2012 and February 2016, North Korea launched long-range rockets in a southward trajectory, which the country said placed more satellites into space.

In both cases, the rockets flew south, potentially crossing over small Japanese islands like Okinawa that are northeast of Taiwan in the East China Sea -- but these missiles did not cross over one of Japan's four main islands.

As in 2009, North Korea issued a warning to mariners and pilots in the region prior to each launch, Davenport said.

Despite the 2009, 2012 and 2016 launches being related to satellites, critics were quick to assert North Korea was using them as cover for testing related to their ballistic missile development.

Davenport said that while North Korea can gain information relevant to the ballistic missile program through satellite launches, there are important technological differences when comparing satellite and ballistic missile tests.

"... While satellite launches give North Korea information relevant to ballistic missile development, [the] international community should not discount Pyongyang's interest in space," she said. "The motivations are not mutually exclusive."

The 2012 launch of what North Korea claimed to be a weather satellite took place in mid-December, only a year after Kim Jong Un assumed power following his father's death.

August and September 2017

In August and September 2017, North Korea launched a missile over Japanese airspace, according to the U.S. Pacific Command.

On August 28, the missile flew over the northern island of Hokkaido and landed in the Pacific Ocean. The test was in response to President Trump’s suggestion that North Korea would be “met with fire and fury” if it continued to threaten the U.S.

The Sept. 14 intermediate range ballistic missile, the second one in a month, originated from Sunan, North Korea and flew east over Japan near Hokkaido, the same prefecture under which a KN-17 traveled in August.

This latest launch is the 14th missile test conducted by North Korea in 2017. On September 3, North Korea said it tested a hydrogen bomb, leading to sanctions being passed against the country by the United Nations Security Council on Tuesday.

North Korea has now launched five missiles over Japan.