What happens if North Korea launches a first strike at the US?

The US monitors North Korea using various means, including satellite imaging, intercepted communications, and spies within the country.

Private firms with government funding are also working on satellite-based radar that could watch for launches even through cloud cover, which can block conventional satellite imaging.
If North Korea were to launch a missile, the US could spot it and work out where it’s heading, but intercepting it would be much harder.

America has three lines of defensive rockets that could take out an ICBM, in increasing order of distance from North Korea, according to ABC News:

in south Korea, on US Navy ships in East Asia, and in Alaska and California.

They’re not a guaranteed defense, however.

Could the Terminal High Altitude Area Defense system (THAAD) that the U.S. is installing in South Korea protect the country from an attack by the North?

The problem with relying on missile defenses is that they are not good enough to replace efforts to solve the problem directly through diplomacy.

You might think a missile defense system is an insurance policy, but it’s hard to have a lot of confidence in that technology.

Ther is a study done a year ago by  the U.S. Ground-Based Midcourse Defense system based in California, and they found that even under controlled test circumstances it has a 50 percent failure rate.

That’s a reflection of several things:

One is that it’s a very hard technical problem to hit a bullet with a bullet.

Also, the program behind the system has not been run very well.

It was exempted by former Pres. George W. Bush from the standard fly-before-you-buy oversight and testing rules, and so it’s been able to go forward without jumping through the hoops that Congress finds—again and again—are important to make these things work.

And these intercept tests are incredibly expensive, about $2 million each.

The missile defense complex at Fort Greely, Alaska. Photo: Missile Defense Agency

The Pentagon’s main tester has said the missile defense system has no demonstrated operational capability, which we agree with.

And yet people are saying that they could shoot down North Korean missiles, they have a 90 percent chance of success.

I worry about political leaders who don’t understand the technical issues, thinking that they have capability that they don’t actually have.

If Pres. Trump thinks that we could launch an attack on North Korea and then defend ourselves using THAAD or the Aegis Ballistic Missile Defense system, then it could lead to bad decisions.

What other options does the U.S. have to defend itself from North Korea’s arsenal?
Most of the defense systems are intended to work as a missile passes out of the atmosphere, during the midcourse phase, because once you’re above the atmosphere things move on a predictable trajectory.

The problem is that outside the atmosphere it’s also easier to deploy decoys that can confuse a missile defense system—things have the same trajectory above the atmosphere regardless of their mass.

One thing the U.S. doesn’t appear to be working on now—which is a bit of a mystery to me—is so-called boost-phase missile defense, which attempts to hit the missile while it’s still burning early in flight.

A missile burns for its initial three to five minutes of flight.

During that time it’s a large target that’s moving relatively slowly and is easy to see.

The problem is that because boost time is short you need to be relatively close to the launch site to be able to do it.

But North Korea is a small country surrounded by water—it was made for boost phase missile defense positioned on ships.

If you’re really worried about North Korea and want to develop a missile defense system, that’s probably the way you’d want to go.

THAN …….

If a nuclear-tipped missile were hurtling toward the United States, would we be able to stop it?

Maybe, if we were very lucky.

But some experts warn that the United States’ missile defense system isn’t as reliable as people might think.

Right now, a constellation of sensors and 36 interceptor missiles make up the ground-based midcourse defense system, or GMD.

It’s intended to act as insurance against a small-scale nuclear attack from North Korea, or possibly Iran, according to the Department of Defense.

(Neither country has missiles capable of reaching the US, although US officials say North Korea is getting closer.)

It’s not meant to ward off an unlikely attack from the much larger and more sophisticated arsenals of Russia or China — nor would it be able to.

Still, it’s the only defense we have against an intercontinental ballistic missile or ICBM once it’s in the air.

On May 30th, 2017, the US tested these defenses against an ICBM-like target for the first time.

To stop it, a ground-based interceptor missile fired from Vandenberg Air Force Base collided with the incoming warhead and smashed it to smithereens.

The test appears to have been a success — but that doesn’t necessarily mean the GMD could stop an enemy weapon under real-world conditions.

In fact, the Government Accountability Office — a nonpartisan government agency also known as the congressional watchdog — reported in 2016 that the GMD “has not demonstrated through flight testing that it can defend the U.S. homeland against the current missile defense threat.”

HOW IS OUR MISSILE DEFENSE SYSTEM SUPPOSED TO WORK?

For a second, let’s imagine a frightening future where North Korea actually does have working ICBMs — and decides to launch one. Satellites with infrared sensors and radar systems deployed in Japan and on US Navy ships would spot the missile launch, and alert control centers in the US. Sensors, including a sea-based, high-resolution radar, would track the hostile missile as it flies.

When the missile leaves the atmosphere, it enters longest phase of its flight called the midcourse.

At this point, the missile breaks up into the warhead, debris, decoys intended to confuse our sensors, and the last stage of the burned-out rocket booster.

On the other side of the Pacific, people in control centers in Alaska and Colorado would work quickly to find the warhead and figure out where to intercept it.

Then, they give the order to fire interceptor missiles from Vandenberg Air Force Base in California, or Fort Greely, Alaska.

There are 36 interceptors stashed in silos at these two sites, each carrying a “kill vehicle” on a three-stage rocket booster.

(Tom Karako, a missile defense expert with the Center for Strategic and International Studies, describes the kill vehicle as a “funny looking telescope with a jetpack attached to it.”)

As the interceptor leaves the atmosphere and enters space, the 120-pound kill vehicle and the rocket separate.

Using infrared sensors to find the incoming warhead, the kill vehicle moves into the warhead’s path by firing its own little thrusters.

When the two objects collide, the kill vehicle should, theoretically, obliterate the warhead without causing a nuclear detonation.

 Image: Missile Defense Agency