Experts say Japan needs to hit back, or North Korea will send more missiles their way

When North Korea fired a missile over Japan, it violated the island nation's sovereign territory and defied the United Nations, and if Japan doesn't do anything about it, experts say Pyongyang will likely walk all over them.

North Korea has reached a point with its long-range missile tests where it needs to fire them on normal trajectories, which means overflying Japan.

The North Korean ICBM tests flew almost straight up in the air and landed only a few hundred miles away when they're meant to travel thousands of miles away.

Now North Korea needs to find out how to guide the warheads when they're actually flying at something.

"There is a technical imperative for conducting this test. They want to be able to look at re-entry dynamics and how it performs on a more normal trajectory," Mike Elleman, a missile expert at the International Institute for Strategic Studies, told the Washington Post.

Given North Korea's need for these kind of tests over Japan, if Japan doesn't respond strongly enough, it can only expect the tests to continue.

"In a way, it's kind of a trial balloon. If we overfly Japan, what happens? If the blowback isn't too significant, they will feel more comfortable with launching a Hwasong-14 to a good distance to validate its performance on a normal trajectory," Elleman said.

"NK missile flight over Japan is an Archimedean point for the US," Tal Inbar, the head of the space research center at the Fisher Institute for Air & Space Strategic Studies tweeted after the launch. "No REAL ACTION - and we will see more missiles on the same path soon."