A South Korean soldier on Wednesday walks past a television screen in Seoul showing a graphic of the distance between North Korea and Guam.

A South Korean soldier on Wednesday walks past a television screen in Seoul showing a graphic of the distance between North Korea and Guam. | Jung Yeon-Je/AFP/Getty Images)

Everything you need to know about the North Korea nuclear threat

Tensions between the United States and North Korea may have reached a new boiling point, but they’ve been simmering for decades.

Here’s a rundown of where each side stands and what the options are ahead.

What nuclear and missile capabilities does North Korea have now?

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North Korea demonstrated last month that it can launch an intercontinental ballistic missile with the power to reach several major cities on the U.S. mainland. The July 28 missile was launched straight up in the air, but experts extrapolated that it could hit cities like Denver or Chicago if it were launched in a normal, flattened trajectory.

The Washington Post also reported Tuesday, citing a new analysis by the Defense Intelligence Agency, that North Korea had successfully made a miniaturized nuclear warhead. The Pentagon has long said that it has operated under the assumption that the North Koreans already had this capability.

It's unclear, though, whether the North Koreans have designed a reentry vehicle capable of protecting the warhead. Without this capability, the missile and warhead would burn up upon reentering Earth’s atmosphere.

What can the U.S. do to defend itself and its allies?

The U.S. has a missile defense system for the mainland. The ground-based midcourse defense system has 36 interceptors in the U.S., split between Fort Greely in Alaska and Vandenberg Air Force Base in California.

This system successfully intercepted an ICBM target earlier this year, but it has failed three of its five total tests. As a result, experts have questioned whether the system could actually defend the U.S. from the North Korean threat.

In the Pacific, South Korea and Guam have the Terminal High-Altitude Area Defense System , which can destroy short, medium and intermediate-range missiles in the final stage of their flight but is not designed to take down ICBMs.

The U.S. Navy can also deploy ships with the Aegis Ballistic Missile Defense System, designed to stop threats from short- to intermediate-range missiles, but not ICBMs.

What does the U.S. have in its nuclear arsenal?

The U.S. nuclear triad is made up of three parts: bombers in the air, submarines under the water and ICBMs on the land. While the Trump administration is reviewing the country’s nuclear posture, most expect the premise of having three ways to launch a nuclear strike will continue.

The Air Force has 20 B-2 bombers and 54 nuclear-capable B-52 bombers, according to a Congressional Research Service report in February. The Navy has 14 nuclear-capable submarines, each of which can carry 24 Trident II missiles, the report said. The land-based portion of the triad includes 414 Minuteman III ICBMs.

Each leg of the triad is also undergoing expensive modernization. The Air Force has awarded a contract for the B-21, a new long-range strike bomber to be built by Northrop Grumman. The Navy is working on the Columbia-class submarine to replace the current fleet. And the Pentagon is also working on a new ground-based strategic deterrent.

The total modernization cost is estimated at about $1 trillion over 30 years.

What conventional military options could the U.S. use to respond?

The U.S. also has non-nuclear options to respond to the North Korean threat. It could launch Tomahawk missiles from ships, similar to the strike President Donald Trump ordered to stave off a chemical weapons attack in Syria, according to a report in The Atlantic. It could also conduct airstrikes using conventional platforms.

Most experts agree, however, that countering the North Korean threat with a military response is not a good solution. It could kill millions in South Korea and nearby and endanger thousands of American troops in the region.

At the other end of the spectrum lies the option of withdrawing from the region, with the theory being that the Kim regime might end its escalation if it no longer feels its existence is threatened. But experts again say this is a bad idea, explaining it's politically not viable and could embolden the North Korean regime.

What are the non-military options?

Administration officials have said the U.S. is willing to use military power against North Korea, but have stressed it’s the least desirable option. Many agree that the best solution lies with a non-military response, including more sanctions, diplomacy and negotiations.

Former Defense Secretary William Perry says the best solution may be to offer North Korea economic concessions from South Korea and security assurances from the U.S. in exchange for an end to its nuclear and long-range missile programs.

“I do not suggest this approach with any enthusiasm. But our only realistic alternative is military force,” Perry wrote in the Huffington Post.

Secretary of State Rex Tillerson has opened the door for negotiations between North Korea and the U.S. to begin if the Kim regime stops testing its ICBMs for an “extended period of time.”

Asked how long that would be, he responded that “we’ll know it when we see it.”