Experts break down the North Korean threat amid heightened tensions

Tensions between the U.S. and North Korea reached their highest point in years over the course of this summer, and they don't look as if they will diminish anytime soon.

Increased missile tests by the North Koreans and a change in approach by the Trump administration have taken the two countries' leaders into uncharted territory.

The war of words between North Korean leader Kim Jong Un and President Donald Trump further escalated Tuesday when Trump, in his first speech before the United Nations General Assembly, slammed Kim, saying, "Rocket Man is on a suicide mission for himself and for his regime."

Though much about the so-called Hermit Kingdom's inner workings remain a mystery, more and more information about its military programs and arsenal is becoming clear. Ahead, what we know about the North Korean threat.

The North Korean mindset

Steve Ganyard, an ABC News contributor and a former deputy assistant secretary of state, was quick to note that nobody really knows what motivates Kim but "the consensus in the intelligence community is that he's trying to use nuclear weapons for regime stability and the ability to make the U.S. think twice about whether they would trade Seoul for Seattle."

Scott Snyder, a senior fellow for Korea studies at the Council on Foreign Relations, agreed that maintaining stability is a major goal, as is projecting a strong image globally and at home.

"I believe Kim Jong Un knows that he's weak and vulnerable and he believes that having nuclear capabilities and an ability to strike the United States will help to remove the vulnerability he feels," Snyder told ABC News.

Snyder also believes that the country's nuclear arsenal helps bolster his legitimacy domestically.

"Having nuclear weapons has become a key to his survival in sustaining his rule because he looks around the neighborhood and the world and sees that he's weak," Snyder said.

He said that while North Koreans call the country's nuclear weapons program "the treasured sword," Kim sees it as "the great equalizer."

In a statement after the country's most recent missile test, Kim said that "he was seeking equilibrium with the U.S.," Snyder said.

"In that statement, he's showing his concern about North Korea's vulnerability," Snyder added.

There may be a more tangible goal as well, Ganyard said.

"I think there's also a growing sense with many people that his ultimate goal is a reunification of the Korean Peninsula under his control," Ganyard said. "That's even more scary, because that's a very offensive mindset that he thinks he can keep the U.S. at bay and that he can defeat the South militarily. Now that's highly, highly unlikely, but history is replete with conflicts that have been started by miscalculations."

Missile launches

North Korea has conducted 14 ballistic missile tests so far this year.

The first came in February, when the North launched a solid-fuel, intermediate-range missile that traveled 310 miles into the Sea of Japan.

Gen. John Hyten, the commander of U.S. Strategic Command, told a congressional panel in early April that the February launch marked a significant advancement for North Korea because it was its first successful solid-fueled missile fired from a mobile launcher, which makes those missiles harder to track because they can be positioned and fired on short notice.

Subsequent missiles have flown increasing distances, reaching more than 600 miles in one March test of a medium-range Scud-er (extended range).

There was a series of missiles that failed before reaching greater distances, but their capabilities reached new heights on July 4. That was when North Korea launched, for the first time, a two-stage intercontinental ballistic missile to mark the United States' Independence Day.

The missile was launched into a high-altitude trajectory, going 1,730 miles vertically and about 577 miles horizontally and landing in the Sea of Japan. Three weeks later, another ICBM was launched and went even farther.

The latest missile was launched on Sept. 14, and Japanese broadcaster NHK reported that the missile flew as much as 478 miles up and about 2,300 miles horizontally.

According to the South Korean Joint Chiefs of Staff, if angled correctly, that ICBM could travel as far as Washington, D.C., or New York.

Nuclear arsenal

North Korea has a small arsenal of nuclear weapons, the existence of which have been proved by the country's five nuclear tests. A 2016 Congressional Research Service report estimated that North Korea has 66 to 88 pounds of separated plutonium, enough for at least half a dozen nuclear weapons.

U.S. intelligence agencies believe that North Korea now has an arsenal of as many as 60 nuclear devices.

North Korea is working toward its stated goal of placing a nuclear warhead on an ICBM capable of reaching the United States.

U.S. intelligence agencies concluded that North Korea tested a hydrogen bomb on Sept. 4, according to a U.S. official.

Military technology

Ganyard said North Korea would need to have four essentials in place before being able to strike the U.S. with a nuclear weapon: the weapon itself, missiles capable of carrying it, technology that allows the missiles to re-enter the earth's atmosphere without burning up and the capability to target missiles.

Kim "showed us that the rocket has the range" necessary to strike most of the U.S. through recent missile tests, Ganyard said. A U.S. Defense Intelligence Agency report and a recent test of a thermonuclear weapon 20 times as powerful as the bomb dropped on Hiroshima have led officials to believe the country possesses a nuclear weapon that could be placed on a missile.

Whether Kim has the missile re-entry technology and missile-targeting capability necessary for such an attack remains a mystery. Ganyard said it's "still doubtful" that North Korean forces have the re-entry technology needed to have a nuclear weapon explode at its most destructive state. A recent missile test also appeared to show that the bomb that they had tested "disintegrated before fully reentering," Ganyard said.

The North's ability to target missiles remains totally unknown.

"We have no idea where he stands on that technology," Ganyard said.

Just what kind of re-entry and targeting technology North Korea has remains an open question.

"Even with the [Defense Intelligence Agency] report out there, I would still say that they have an unproven capability to deliver because there has not been a judgment yet about their ability to master re-entry to the earth's atmosphere, so that applies for now to the continental United States," Snyder told ABC News in August.

What the recent thermonuclear test showed, he said, is that the North has nuclear capabilities.

"More importantly, the size of the yield was large enough that it reduces the need for accuracy in the event that North Korea wants to strike a location in the United States," Snyder said this week.

He warned that North Korea's re-entry abilities could change in the coming months.

US defense systems

As part of a security commitment the U.S. made to South Korea after the Korean War, 28,500 American troops are permanently stationed in the South. Additionally, there are there 54,000 American troops stationed in Japan.

Beyond simple manpower, the United States has a layered missile defense system designed to track and intercept missiles launched from North Korea.

It includes missile interceptors aboard Navy ships in the Pacific and large ground-based interceptors in Alaska and California. However, the viability of the large interceptors has been routinely questioned since they became operational nearly a decade ago.

In late May, the Missile Defense Agency successfully tested an interceptor that targeted a test ICBM fired from Kwajalein Atoll in the South Pacific.

The Terminal High Altitude Area Defense system is a missile defense shield designed to intercept short-, medium- and intermediate-range missiles.

In April the United States deployed THAAD to South Korea for the first time, a long-planned move agreed to last summer after a series of 2016 North Korean missile tests. The U.S. has also placed the THAAD system in Guam, which could be reached by some of North Korea's long-range missiles.

Shifts in rhetoric

The overtly aggressive rhetoric that Trump has been using toward North Korea, coupled with the country's increasing number of missile tests, has brought to the fore the question of what happens next.

While that remains unclear, Snyder suggested that the tests are tied to the rhetoric.

Since taking office, Trump has said that North Korea is a "rogue nation," a "great threat," "hostile and dangerous," "looking for trouble" and "behaving very badly." In August he said that if North Korea didn't stop threatening the U.S., it would be met with "fire and fury like the world has never seen." Most recently, he has taken to referring to Kim as "Rocket Man."

Those comments coincide with an increase in tests, Snyder said.

"The North Koreans have been pretty consistent in playing tit for tat and responding to threats of pressure with threats of pressure," he said.

"Within the past months, the escalation in rhetoric has been on the U.S. side - not to point any fingers - and the North Koreans have responded in kind," Snyder added.