Seoul, South Korea
CNN
 — 

North Korea fired a ballistic missile without warning over Japan on Tuesday for the first time in five years, a highly provocative and reckless act that marks a significant escalation in its weapons testing program.

The missile traveled over northern Japan early in the morning, and is believed to have landed in the Pacific Ocean. The last time North Korea fired a ballistic missile over Japan was in 2017.

This marks North Korea’s 23rd missile launch this year, including the most ballistic missiles fired in a single year since leader Kim Jong Un took power in 2012. By comparison, Pyongyang conducted four tests in 2020 and eight in 2021.

Here’s what you need to know about North Korea’s missile tests.

Tuesday’s missile flew a distance of about 4,600 kilometers (2,858 miles), with an altitude of some 1,000 kilometers (621 miles) and a top speed reaching Mach 17 – meaning 17 times the speed of sound, according to Japanese officials.

By way of comparison, the US island territory of Guam is just 3,380 kilometers (2,100 miles) from North Korea.

Two experts told CNN these flight details suggest the missile fired was likely a Hwasong-12 – an intermediate-range ballistic missile (IRBM) last tested in January.

“This is a missile that North Korea started testing in 2017 … So it’s not really a new missile,” said Jeffrey Lewis, director of the East Asia Nonproliferation Program at CNS.

But, he added, its launch is significant because of the distance it can travel.

“North Korea has a bunch of missiles that are shorter range, and that wouldn’t go over Japan – but they have a small number of missiles that could make that journey,” he said.

North Korea usually fires its missiles into waters off the coast of the Korean Peninsula – making this flight over Japan considerably more provocative, for both practical and symbolic reasons.

This kind of unannounced launch could pose risks to aircraft and ships as the missile travels down to its target, since they would have no prior warning to avoid the area.

And if the test had failed, causing the missile to fall short, it could have endangered major population areas of Japan.

In the past, US planes have been grounded as a ‘precaution’ following North Korean missile launches. And in late November 2017, several commercial jet pilots were reported to have seen what appeared to be the re-entry of a North Korean missile as it approached the Sea of Japan.

However, Lewis emphasized, such risks are statistically low, especially that far out in the Pacific and that high above Japan as it flew overhead. Mostly, it’s an escalation simply because “it’s provocative to fire a missile over your neighbor.”

“For the Japanese especially, it feels like a violation of their sovereignty,” Lewis said. “If Russia fired a missile over Florida, we would have a fit.”

And, experts say, it’s a sign of Kim’s ambitions for North Korea’s weapons development – and of what’s yet to come.

There are differing opinions on what may have driven North Korea to fire Tuesday’s missile.

Robert Ward, senior fellow for Japanese Security Studies at the International Institute for Strategic Studies, pointed to the multiple security threats faced by Japan, from an aggressive Russia to its north and China to its south.

“North Korea may be trying to exploit the unstable international situation, which it will see as a tailwind,” he said.

Lewis disagreed, saying that although North Korea sometimes responds or retaliates to specific actions by Western players or groups, for the large part “they have their own schedule … and I don’t think that we have a lot of impact on the timing.”

There are also practical reasons; North Korea often takes breaks in testing during the summer when weather is bad, and pick up again once the fall and early winter arrive – meaning now could just be the right conditions for a test, he added.

Joseph Dempsey, research associate for defense and military analysis at the International Institute for Strategic Studies, added that Tuesday’s flight path could just make for a better test.

These types of missiles are meant for long-range targets – so flying it over Japan could help North Korea gauge its accuracy over a longer distance, its ability to withstand different forces exerted on the missile, and other factors, compared to its usual “lofted” tests – which travel higher in altitude and splash down west of Japan.

Kim had vowed earlier this year to develop North Korea’s nuclear arms at the “highest possible” speed – and experts say Tuesday’s launch is part of that push for weapons advancement.

“North Korea is going to keep conducting missile tests until the current round of modernization is done,” Lewis said, adding that a nuclear test could come “anytime.”

South Korean and US officials have been warning since May that North Korea may be preparing for a nuclear test, with satellite imagery showing activity at its underground nuclear test site.

If North Korea conducts a test, it would be the country’s seventh underground nuclear test and the first in nearly five years.

There are also other missile tests to watch. Apart from the Hwasong-12, North Korea also has three intercontinental ballistic missiles (ICBMs) capable of flying over Japan, though these have not been tested “to their full range yet,” said Lewis.

“This is probably an appetizer for the main course, which is yet to come,” he added. “I would expect that when North Korea has more confidence in one of their ICBMs, they might fly one of those to full range over Japan.”

Leif-Eric Easley, associate professor of international studies at Ewha Womans University in Seoul, added that North Korea could be waiting until after China holds its Communist Party Congress in mid-October to “conduct an even more significant test.”

“The Kim regime is developing weapons such as tactical nuclear warheads and submarine-launched ballistic missiles as part of a long-term strategy to outrun South Korea in an arms race and drive wedges among US allies,” Easley said.