(CNN) North Korea has test-fired a brand new intercontinental ballistic missile (ICBM), which experts said shows a major advance in technology and threat.

Photos of the Hwasong-15 released Thursday by North Korean state media showed a large, tall missile that appears to be significantly wider than the Hwasong-14, previously Pyongyang's most-advanced missile, which was launched over Japan twice in July.

"They wanted (to be able) to hit all of the US and they wanted something big to hit it with," said David Schmerler, a research associate at the James Martin Center for Nonproliferation Studies (CNS). "This seems on the surface level to be that missile."

The US military has begun referring to the missile as a "KN 22" -- a new designation signaling that the US is increasingly seeing the recent launch as involving a new type of ICBM, according to two US defense officials.

The two launches in July were categorized as KN-20s.

Experts have been analyzing and studying the images since their release, so what can we learn from them about North Korea's new weapon?

An image released Thursday, November 30 purports to show the Hwasong-15 missile launched Wednesday.

It's really big

"This isn't just a big missile for North Korea this is a big missile in general," Michael Duitsman, also research associate at CNS, told CNN. "There are not a lot of countries who could build a missile this big and have it work."

Schmerler said it was "a lot bigger width wise, especially the second-stage, than the previous ICBM."

ICBMs use multiple stages, each containing its own engines and propellant, to carry their payloads up into space, around the earth, and then down towards their target.

Photos released by North Korean state media show Wednesday's launch of the Hwasong-15 ICBM.

While North Korea has demonstrated significant potential range in previous missile tests, some experts have cast doubt on whether the same distance could be achieved by a rocket carrying a heavy nuclear warhead.

Pyongyang seemed to clap back at those skeptics in a statement after Wednesday's launch, which said the Hwasong-15 was "capable of carrying a super-heavy nuclear warhead."

"This system has much greater advantages in its tactical and technological specifications and technical characteristics than (the) Hwasong-14," a government statement said.

The missile was launched just before 3 a.m. on Wednesday, November 29 via a mobile launcher.

While Schmerler cautioned that it was "hard to look at something and know there's a heavy object" on top of it, he said North Korea's claims should be taken seriously and Wednesday's test likely was conducted with a dummy warhead equivalent in weight to a nuclear bomb.

"They're going to try to maximize the amount of (information) you can get out of each test," he said. "They're not going to launch something for the sake of it, it makes much more sense for them to try and field a realistic decoy payload."

Shea Cotton, also a CNS research associate, said he didn't "see why they wouldn't test something with a heavy payload, when we're pretty sure they already have a missile that can hit the US."

Japanese defense minister Itsunori Onodera said Thursday the Hwasong-15 appeared to be a "new type of ICBM-class ballistic missile ... with considerable capability."

"We have never sought war with North Korea, and still today we do not seek it. If war does come, it will be because of continued acts of aggression like we witnessed yesterday," she said. "And if war comes, make no mistake, the North Korean regime will be utterly destroyed."

Experts agreed the Hwasong-15 appears to be larger than any missile North Korea has built previously.

It has a brand new engine system

The Hwasong-14 , previously North Korea's most advanced ICBM, uses one primary engine with four steering thrusters to guide the missile where it needs to go.

Tuesday's launch however appeared to use two engines, without any supplementary thrusters. "This is certainly a big adjustment," said Schmerler. "It means they've probably gimbaled the engines ... something we've never seen the North Koreans do."

"Gimbaling is something we've never seen in North Korea before, (if we're right) then this would be brand spanking new for North Korea," he said.

In a gimbaled system , rather than having fins or thrusters guide the rocket, the exhaust nozzle of the engine itself can be moved from side to side, adjusting its course.

North Korea's most advanced intercontinental ballistic missiles (ICBMs), the Hwasong-15 (left) and Hwasong-14.

Schmerler said that while all countries draw on foreign designs for their weapons systems to some extent, and learn from what competitors and allies do, this would represent a major advance for the domestic North Korean missile program.

"They're looking at the rest of the world and seeing what works and what doesn't and applying this to their own program," he said.

On Twitter, several analysts compared the Hwasong-15's engine to that of the Titan II , a US missile developed during the Cold War and retired in 1987.

North Korean leader Kim Jong Un inspects the Hwasong-15 before its launch Wedneday.

There's likely another test to come

Following Wednesday's launch, a North Korean official told CNN Pyongyang was not interested in diplomacy with the US until it had fully demonstrated its nuclear deterrent capabilities.

Reiterating remarks made in the past, the official said one step was to conduct an above-ground nuclear detonation or "large-scale hydrogen bomb" test. The other was the "testing of a long-range ICBM," the implication being this had been achieved with the most recent launch.

A government statement said the Hwasong-15 "is the most powerful ICBM which meets the goal of the completion of the rocket weaponry system development set by (North Korea)."

But Schmerler said this does not mean the North Korean program will not continue advancing, especially if relations with the US do not improve: "They may feel the technological development they've achieved is not sufficient to bring the Americans to the table."

Even if the Hwasong-15 fulfills the end goal of years of missile development, Duitsman said, Pyongyang will likely want to test the system "at least one more time" before it is satisfied with its effectiveness. Two tests of the Hwasong-14 were carried out within weeks of each other in July.

"They also might still conduct practice launches," said Cotton. "To get good at launching (the missiles) in the event they have to launch them really quickly.. so we could see a few of those."