Do North Korean missile tests really violate Japanese airspace?

DPRK’s [North Korea’s] latest series of unarmed missile tests have been described as flying over Japanese airspace, a fact which has led to much panic and debate over how to respond to this perceived “threat.” A typical headline was this one published by NBC News: “North Korea Fires Ballistic Missile Over Japanese Airspace Again.”

These news reports have all implied that these tests are a violation of Japan’s sovereignty and possibly acts of war, but they have all been tolerated without an aggressive response. There certainly is good reason to feel uneasy about the launch of a missile that is capable of carrying weapons of mass destruction. There is no way to know that the missile is unarmed and is just being tested. The Japanese might be thinking, “What kind of country would commit a surprise attack without declaring war first? ... Oh, yeah, right.” A thief worries more than normal people about his belongings being stolen.

In earlier days, North Korea used to inform the appropriate authorities about its plans to carry out tests, but in the present heated context, when adversaries threaten to shoot down their missiles, the North Koreans are disinclined from revealing their plans. The international community is right to be alarmed by the recent missile tests, but it is failing to discuss with the public some essential questions about the laws and normalized practices regarding the testing of long-range missiles.

I tried to find out whether North Korea really has violated Japanese airspace, and whether it is doing anything that hasn’t been done by other countries. Information is not easy to come by. For all the reports that have appeared in the mass media about North Korea’s missiles and nuclear tests, none of them have answered this fundamental question.

All one can conclude from Internet searches is that this is a case of something being allowed only because it is not expressly forbidden by international law. Sovereign airspace only extends up to 100 km, and North Korea’s missiles pass over Japan in a parabolic arc that goes much higher than this into the levels occupied by satellites and the International Space Station. If sovereign airspace extended beyond the atmosphere, it would be “spacespace,” not airspace, and every orbiting man-made object would be in violation constantly. Furthermore, we have to wonder which other countries have tested missiles, or used armed missiles in war, without asking permission to fly over or through the airspace of other nations. There is very little information available on this topic.

The telltale word in the headlines may be that word “over” in the NBC News headline. The writers chose to say “over” but not “through Japanese airspace.” If the missile had gone through Japanese airspace that would have been more clearly a threatening act of war, but since it went over Japanese airspace, North Korea is doing nothing technically illegal.

After searching for discussions of this issue, I found a few interesting responses on Stackexchange.com, but it is impossible to confirm the expertise of these sources. “Affable Geek” wrote, and “Yannis” responded:

When flying over another country’s airspace, the laws of that country apply. Alcohol, for example, can be banned on certain flights due to international recognition of a foreign power’s rights.

That said, spy satellites, Voyager, and the International Space Station don’t seem to fall under these rules. This seems to imply an upper limit.

So the question is, how high would an aircraft need to fly in order not to be subject to these rules?

Satellites, the (discontinued) shuttle project and ISS are governed by space law, national airspace laws don’t necessarily apply, or are supplemented/amended by international/bilateral agreements, on a case by case basis.

That said, the vertical extent of national airspace is a matter of debate. A logical upper limit is the point where outer space begins, as outer space is not subject to national laws. However, the boundary is also a matter of debate: FAI [Fédération Aéronautique Internationale] considers the Kármán line (100 Km from sea level) to be the boundary. (2013/06/04)

In another post, “bobuhito” sums up the legal and moral considerations well by writing:

If they exceed 100 km in height above Japan and land further than 23 km from Guam, it can be argued as legal. Additionally, they need to reasonably clean up after themselves and not just leave a spent missile in the sea.

To be polite, they should also announce the launch time and path in advance. To be nice, they should cancel. There’s too much risk of a mistake killing people, and the best-case outcome still contributes to global warming. (2017/08/12)

(See also: https://en.wikipedia.org/wiki/Airspace)

In the meantime it would be nice if experts, journalists and the leaders of North Korea and of the countries affected by these missile tests could clearly articulate what they believe to be the rules and accepted norms for tests of long-range missiles and rockets, all of which are conceived, according to conceptions preferred in particular circumstances, as deployed for peaceful or defensive purposes, or for acts of aggression. No one wants a war to begin at this time just because of one nation’s, or one leader’s, subjective sense of “feeling threatened.”