North Korea conducted their sixth nuclear test on Sunday, this time of a significantly more powerful weapon believed to be a two-stage, or hydrogen bomb.

Because North Korea has conducted all of its nuclear testing, Sunday’s included, underground in their Punggye-ri complex, details are sparse, but intelligence gathered from seismic readings suggest that Kim’s claims are likely accurate, and that North Korea now possesses the means to produce dramatically more powerful nuclear weapons than ever before; ten times more powerful than their last test, conducted in September of 2016, according to reports from both Japanese and South Korean officials.

According to estimates, Sunday’s test was conducted using a bomb with a yield believed to be 120 kilotons.  As a frame of reference, the bombs dropped on Hiroshima and Nagasaki at the end of WWII were 15 and 20 kilotons respectively.  This advancement indicates that Kim’s nuclear weapons have now graduated into modern-city killers, in terms of destructive power.

“That scale is to the level where anyone can say (it is) a hydrogen bomb test,” said Kune Y. Suh, a nuclear engineering professor at Seoul National University.  “North Korea has effectively established itself as a nuclear state. This is not just a game changer, it’s a game over,” Suh added.

Prior to the test, North Korean media outlets shared photos that showed Kim Jong un inspecting a peanut shaped nuclear device, indicating that the detonation was indeed of a two-stage weapon.

The bomb North Korea showed today, if you look at the shape, the front part looks like an atomic bomb which triggers nuclear fission and the back part, a second stage that generates nuclear fusion reactions,” said Chang Young-keun, a rocket science expert at the Korea Aerospace University.

These two stage devices use a traditional atomic bomb to set off a chain reaction that produces a second, much larger blast.

“This means explosions can happen double and triple. And that’s why its power is great. Even if it’s the same size and weight, if it’s a hydrogen bomb, its power can be tens or hundreds times bigger,” Chang said.