A single Intercontinental Ballistic Missile, also known as an ICBM, is being launched toward
the United States to carry on a nuclear attack.
Of course if this was a full blown nuclear war, hundreds of ICBMs and Submarine Launched
Ballistic Missiles would be launched, in which case, it’s exactly what you think; Kaput,
PIZDEZ, Game Over!
You simply cannot stop a raid of hundreds of ICBMs, each carrying tens of nuclear warheads.
But what it takes to even intercept a single ICBM, is Not What You Think!
It can take up to 30 seconds to detect the launch of an ICBM, depending on the weather.
If it’s cloudy, as soon as the rocket rises above clouds, the missile’s exhaust would
be detected by infrared sensors, either on the older Defense Support Program Satellites
or newer Space-Based Infrared System.
Once an ICBM is detected by multiple satellites, an accurate trajectory of the booster can
be calculated, but not necessarily its target.
Thus a decision has to be made by command and control.
Is the missile hostile, or could it be just an exercise?
The reality is that a simple test launch could be viewed as provocative and start a nuclear
war.
For this reason, the United States has recently canceled a Minuteman III ICBM test because
of increased tension with Russia due to their invasion of Ukraine.
But once the decision is made to fire an interceptor, there would be multiple opportunities to shoot
down the ICBM, since ballistic missiles go through three phases of flight: boost phase,
mid-course phase, and terminal phase.
Arguably, the easiest time to shoot down an ICBM is during its boost phase, but ironically,
the least practical one.
Intercepting an ICBM during the boost phase, while the rocket engine is still burning,
is a huge advantage.
Instead of intercepting a small nuclear warhead, it’s much easier to hit a relatively slow,
hot booster that is of monstrous size.
But it is a race against time that makes it impractical.
A typical ICBM burns for about 250 seconds.
As mentioned earlier, it can take up to 30 seconds just to detect an ICBM by satellites,
and it can then take up to 60 to 70 seconds to launch an interceptor missile.
And that’s without taking into account a “decision time”.
This brings the total reaction time to 100 seconds after the ignition of the ICBM, leaving
only 150 seconds to intercept the missile.
Depending on the model, an interceptor has a burn time of about 100 seconds.
Satellite and other ground based sensors can guide the missile toward the ICBM before it
can lock in to the heat signature and strike the ICBM’s structure and not sail harmlessly
through the tenuous flame.
This would be known as “Hit to Kill”.
While older and less advanced systems would get close to the target, and use proximity
fuse to detonate an explosive warhead, the hit-to-kill interceptors rely on kinetic energy,
that is, the interceptor’s mass and speed, to directly hit the target head-on and destroy
it.
What follows a successful strike is a “shoot-look-shoot” tactic which confirms whether the missile
has been destroyed before launching another interceptor.
This minimizes the number of interceptors required to defeat incoming missiles.
As you will find out soon, that is very important.
On paper, it's relatively easy to destroy a nuclear missile during its boost phase.
In practice, however, you have severe reach-versus-time challenges for intercepting during boost phase.
First challenge is that the command & control has little time to decide whether to fire
an interceptor.
If making the decision takes more than a minute, if not less, the interceptor will not reach
the ICBM before its boost phase ends.
To overcome this “time challenge”, it was proposed to use a weapon that travels
at the “speed of light”.
A powerful laser!
The goal of the YAL-1 airborne laser system was to shoot down enemy ICBMs during their
boost phase, from a distance of 115 to 200 miles depending on the type of missile.
However, the laser turned out to be not effective since the atmosphere diffused the laser's
energy more than it was originally anticipated.
The effective range turned out to be measured in “tens” of kilometers which meant that
the Boeing 747 on which the laser was mounted would have to be flying within enemy airspace.
No ship Sherlock, the program was canceled.
The Second challenge is range.
The interceptors would have to be launched from a relatively close location to the ICBM’s
launch site which would make it vulnerable to attack itself.
Some say the lower bound is 30 miles, and the upper bound is 620 miles downrage.
Regardless, this is a big issue!
It may work in case of intercepting a rocket launched from North Korea, but not if launched
from the middle of Russia and China.
While the American SM-3 Missile, which can be launched from either Navy Ships or Aegis
Ashore, has the capability to intercept ICBMs during boost phase, it is not viewed as a
viable option due to the range-time problem.
The American missile defense system currently does not have any practical capability to
destroy ICBMs during the boost phase.
There is, however, research being conducted on new technologies with a focus on Unmanned
Aerial Vehicles.
The boost phase may be out for now, but destroying a nuclear missile during its mid-course phase
provides the largest time interval to do so, which is about 20 minutes.
Seems like a lot of time, but accomplishing this task might be more difficult than hitting
a bullet with another bullet.
Ballistic missile travels at a speed of about 15,000 miles per hour.
That’s 9 times faster than the speed of an average bullet.
There are two ways Americans can intercept a nuclear warhead during the midcourse phase.
Using a Ground Based interceptor, or using a Standard Missile 3 Block II Alpha that can
be launched from Aegis cruisers and destroyers.
The Ground-Based Interceptor, is part of a $40 billion dollars Ground-Based Midcourse
Defense Program, which is one layer of the American Ballistic Missile Defense System,
intended to protect the United States from intermediate and long range ballistic missiles.
A Ground-Based Interceptor is a multi-stage, solid fuel booster with an Exo-atmospheric
Kill vehicle or EKV.
Exo-Atmospheric means “outside of atmosphere”, thus the EKV is like a little spacecraft which
relies on thrusters to maneuver, since the fins cannot help with steering outside the
atmosphere.
This in contrast to endo-Atmospheric, meaning “within atmosphere”, where the vehicle
is maneuverable through aerodynamic forces.
A booster carries the EKV toward the target's predicted location in space, and when it’s
released, it uses guidance data transmitted from Ground Support & Fire Control System
components, as well as on-board sensors to close in and destroy the target.
Each Ground-Based Interceptor requires its own Silo, and all 44 interceptors owned by
the United States are currently located at Vandenberg Air Force base in California or
Fort Greel, Alaska.
Each interceptor costs a whopping $75 million dollars.
Aside from the ground-based interceptors, another way to destroy a ballistic missile
is to utilize the Aegis Ballistic Missile Defense.
Specifically, the SM-3 Block II Alpha that can rely on satellites and other sensors to
track and intercept an intermediate range ICBM.
This is known as “engage on remote”.
The SM-3 is a multi stage interceptor that can be launched from VLS mark 41 from cruisers
and destroyers as well as Aegis Ashore.
The interceptor delivers a “kill vehicle” to space, where it maneuvers to intercept
an incoming warhead.
The biggest challenge for SM-3 interceptors is range.
The launch ship has to be suitably located to intercept an ICBM.
This is why SM-3s are only good at intercepting intermediate range ICBMs, while Ground Based
Interceptors can do both intermediate-range and inter-continental.
So far, things seem more or less under control, until we introduce the next complication:
Decoys.
During its mid-course phase, a typical Russian ICBM, like the R-36 Satan, can release what
seems to be 50 nuclear warheads.
But in reality, only 10 of those are actual warheads, also known as Multiple Independently
Targetable Reentry Vehicles or MIRV.
The other 40 are decoys.
All of a sudden, one ICMB has turned into 50 different moving targets, 10 of which need
to be intercepted.
The defense systems need to have a way to discriminate between decoys and lethal targets
so precious interceptors are not wasted on decoys.
We should also add that other debris, like nose cones, can add to the discrimination
challenge.
While low-resolution radars can track individual objects, they can’t discriminate between
a lethal object versus a decoy.
This is precisely why the US has the Sea-Based X Band Radar whose primary task is to discriminate
lethal targets from decoys, and then perform precision tracking of those warheads.
Another similar radar, the Long Range Discrimination Radar at Clear Space Force Station in Central
Alaska, can similarly discriminate lethal objects from decoys, and forward their trajectory
to interceptor missiles in real time.
The LRDR construction and installations have been completed at a cost of $784 million dollars,
with the final touches currently being performed before the radar becomes operational in late
2022.
The EKV, not only relies on its own sensors to discriminate and perform target selection,
it also uses data from the discriminatory radars that we mentioned
Knowing all this, how many ICBMs do you think the United States can realistically intercept
using its entire stock of 44 Ground Based Interceptors?
Just to demonstrate the complexity of each ICBM having multiple warheads and decoys consider
this scenario.
A single R-36 ICBM can house 10 warheads and 40 decoys.
Assuming that the discrimination radars can correctly identify all 10 lethal warheads,
you’d think the 44 Ground Based Interceptors can successfully neutralize at least 4 ICBMs
carrying 10 warheads each.
But the answer … is Not What You Think.
Each Ground Based Interceptor only has a 56% probability of actually intercepting a single
target.
It would take not two, not three, but four interceptors to increase the probability of
intercepting a single target to 97%, which means a single ICBM with 10 deployed warheads
can easily overwhelm the United States’ entire Ground Based Interceptors and possibly
detonate on American soil.
And this is exactly why the American Missile Defense System relies on multiple layers.
A single line would only be able to destroy a fraction of incoming threats, but combining
multiple lines of defense, last of which is the Terminal phase, can destroy most, if not
all, warheads.
A Terminal phase begins when a nuclear warhead re-enters the atmosphere.
This phase is very short, only takes about a minute, and it’s the last opportunity
to intercept before the warhead reaches its target.
That said, this is the least desirable time for interception because it can occur close
to the intended target, and there is also little margin for error.
Note that when a nuclear warhead is intercepted, it doesn't explode.
In order for a warhead to go critical, the explosive charges need to go off in a specific
sequence, essential to initiate a nuclear explosion.
The result of an interception would be a large spray of radioactive materials near the target
area, which is not good, but it’s much better than a nuclear explosion.
The American Ballistic Missile Defense System can intercept warheads during the terminal
phase using the Terminal High Altitude Area Defense or THAAD, the US Navy SM-6 missiles
launched from warships, or with the US Army’s Patriot Advanced Capability - three missiles.
But there’s a catch.
While viewing the Missile Defense Agency diagram may give you the impression that the defense
systems that we just mentioned can intercept nuclear ballistic missiles, the truth is that
these interceptors can only hit short-range, medium-range and intermediate-range ballistic
missiles.
They cannot shoot down Intercontinental Ballistic Missiles, because those warheads re-enter
the atmosphere at Mach 24+.
Maybe THAAD would be able to hit it head on, but I wouldn’t bet my life on it, because
THAAD’s top speed is less than Mach 9, and is designed to intercept missiles with speeds
of Mach 5 to 8 at a maximum altitude of 93 miles (150km).
An alternative way to shoot down nuclear warheads during their terminal phase is to use endoatmospheric
interceptors armed with small nuclear bombs.
This is exactly the strategy that the Russian A-135 Anti Ballistic Missile System relies
on.
By exploding nuclear interceptors on the border of the atmosphere and space, the A-135 system
can disable incoming warheads traveling at speeds of up to 15,600 mph per hour or Mach
20.
Who would have thought, shooting down nukes, with nukes?
The bottom line is this, shooting down something like an ICBM, while possible, is extremely
complicated.
And we haven’t even mentioned Maneuverable Reentry Vehicles or hypersonic glide vehicles
that can outmaneuver defense systems.
The current goal of missile defense systems is to minimize the threat of rogue nations
like North Korea from launching ICBMs towards American soil, as they are viewed as not being
deterred.
That is, they are not afraid of total annihilation, and might strike anyways.
A recent 2022 study argued that no system thus far developed has been shown to be effective
against realistic ICBM threats.
Even from North Korea.
The Pentagon respectively disagrees.
They feel confident in their abilities and claim that external studies are based on outdated
and inaccurate data due to “classification restrictions”.
The Pentagon aims to develop a next generation interceptor dubbed “never-fail weapon system”.
I suppose we’ll see about that … on a second thought, hopefully, we will never have
to find out.