Is North Korea capable of striking US via Antarctic (South Pole)?

North Korean nukes aimed at the U.S may fly over Russia

The shortest distance between U.S based missiles & the strategic cities of Russia/North korea—and vice versa—is via Canada over the North Pole. Any missile fired by North Korea at the U.S would most likely fly over the North Pole, undoubtedly passing through the Russian airspace.

The other route to avoid flying over Russia is via the South Pole (launching the missile down south) as displayed in the image above. During the Cold War, the Soviets employed the same technique, allowing the missiles to fly over south polar areas to reach the U.S as opposed to going over the North Pole, where much of the US’s early warning radar arrays were located.

Fractional orbit bombardment system (FOBS)

As the Soviets developed ICBM capabilities in the 1950’s & 60’s, the united states constructed a Ballistic Missile Early Warning System (BMEWS) which employed radars to detect the incoming Soviet ICBM's over the north pole. These radars were located at three main sites along Soviet ICBM corridors: Clear AirForce Base, Alaska; Thule, Greenland; & Flying Dales, England. 

The Soviets knew that the BMEW radar systems (soon after detecting an ICBM launch) would give the United states about 15 to 20 minutes of warning time to launch a retaliatory strike. This amount of time (15-20 min) was sufficient for the US bombers (like the B-52) to get off the ground and land-based ICBMs to be launched out of silos.

The Soviets, therefore, developed an orbital weapon system called FOBS (Fractional Orbit Bombardment System) to attack the United States via the ‘backdoor’ i.e, via the South Pole and reduce the warning time to just a few seconds. FOBS would take out the ability to launch a retaliatory strike.

The reason a FOBS would go undetected is because the US at that time had no Ballistic Missile Early Warning (BMEW) radars facing south (all the radars were stationed towards the north pole). Therefore giving little or no warning of an incoming FOBS attack.

Difference between an ICBM and a FOBS capable ICBM

ICBM's travel from continent to continent and follow a sub-orbital trajectory . They exit the atmosphere after being launched, spend most of their flight time outside the earth’s atmosphere and re-enter back over the target. They reach apogee/altitudes of about 800 to 1200 kilometers on normal trajectories.

Whereas in FOBS, ICBM's are fired at a lower, less efficient angle, that is in depressed trajectory (95 km-300 km) instead of normal optimum ballistic trajectory (800-1200km). The warhead is placed into an orbit (steeply inclined polar orbit) as low as 200 kilometers just like any other satellite. The only difference between FOBS and a satellite is, the satellite circles the earth once it is placed into orbit, where as in FOBS the weapon is de-orbited before completing one revolution of earth and hence the name “Fractional”. The weapon system inserted into such an orbit consisted of a nuclear warhead and a de-orbit rocket stage as shown below. 

Dropping bombs from space isn’t as simple as dropping from an aircraft. Bombs dropped from an aircraft would fall freely with out any effort. But that's not the case with the objects orbiting the earth. We need a propulsion system (like the de-orbit rocket stage) to bring it down from space. The FOBS Weapon system is much the same as a satellite revolving around the earth. Satellites stay up (without falling back to earth) because they move fast enough (29,000km/hr) to defeat the downward pull of gravity.

To force a FOBS weapon system out of earth’s orbit, a retro rocket (also known as braking rocket) is fired continuously

for one minute as it approaches the de-orbit entry point (over enemy's mainland). Without a retro rocket, the weapon would remain in orbit for years. 

Also, before de-orbiting the weapon system, you need to re-orient the weapon system first (preparing it for re-entry) and then the retro rocket’s fired to slow down and de-orbit the vehicle, changing the plane of flight from orbital to ballistic. The concept of atmospheric reentry is simple, when an object is circling the earth at greater speeds it stays up there, but when it slows down it won't stay there, but falls back to earth. Retro rockets are fired in the opposite direction of the FOBS motion to slow it down and de-orbit. 

Once the FOBS re-enters earth's atmosphere, the rest of the flight path is same as a normal ICBM warhead re-entering the atmosphere over the target area. The reason we re-orient the weapon system in space is, the target rarely lies directly under the FOBS orbit path.

The main advantage of FOBS is that the enemy would be uncertain when the weapon would be de-orbited onto the target.

Note: ICBMs follow a sub orbital path, Space Rockets go orbital flight, and FOBS travel into partial orbital flight (85% of full orbit). FOBS is just a normal ICBM fired into a depressed trajectory but with an extra de-orbit rocket stage. A missile fired into a depressed trajectory would follow a low orbital path and be difficult for the US radar system to “see.”

How U.S negated FOBS threat?

When the Soviet Union carried out its first successful test of FOBS on Jan 25, 1967— at that time the U.S had the missile early warning satellites called MIDAS capable of detecting missile launches fired at the U.S from any direction (including over the Antarctic or the South Pole).

But MIDAS had problems, it gave false launch alarms as it couldn’t distinguish between missile launches and sunlight reflected off clouds. Also, because of launch and mechanical failures, the MIDAS satellites were unable to provide the desired continuous coverage of the Soviet Union.

The next generation of missile early warning satellites called DSP (DEFENSE SUPPORT PROGRAM) launched in the 70’s succeeded where MIDAS had failed & completely removed the possibility of a surprise attack on the United States with ICBMs & FOBS.

Missile early warning satellites had extended warning time from 15 minutes (with BMEWS) to 30 minutes (with DSP satellites).

Note: All hot bodies emit infrared (IR) radiation. Missile early warning satellites carry infrared sensor or heat sensor to detect the hot plume coming out of the back of the rocket and locate its launch, direction of launch and even identify the type of missile.

As the U.S had no Ballistic Missile Early Warning (BMEW) radars facing south, so, in addition to the existing BMEW radar stations at Alaska, Greenland, and England, a new phased array radar called PAVE PAWS, a cold war early warning radar was added at Beale Air Force Base in California (West Coast) and Otis AFB in Massachusetts (East Coast) as shown below, expanding angular coverage of the CONUS (Continental United States) and rendering the FOBS unusable in its original role.

Furthermore, the outer space treaty of 1967 prohibited the use of space for placing nuclear weapons into earth’s orbit.  The Soviet Union claimed that the FOBS weapon system 
would never complete full orbit and therefore this weapon system didn't violate the treaty, and so continued testing with FOBS until it was banned under SALT II (Strategic Arms Limitations Talks 2) negotiations in 1979.

North Korean EMP attack

In an ICBM, the guidance system is responsible for directing a missile during flight and does fine trajectory corrections. North Korea might have the ICBM range or the FOBS technology, but they lack the necessary guidance capability to deliver nuclear warheads with accuracy. (Here’s link to my article on Guidance systems)

An EMP attack doesn’t need accurate guidance systems because the area of effect is very large (maybe hundreds to thousands of kilometers) and an EMP explosion anywhere over the U.S could cause the same devastating effects. Also, for an EMP attack, you don’t need a re-entry vehicle or heat shield as the detonation is carried outside the atmosphere. Heat shield is required only if an object re-enters the Earth's atmosphere. 

Here are some possible ways an EMP attack could occur:

1) using ICBMs  2) FOBS  3) using Space rockets  (4) and via satellites armed with nuclear warheads.

North Korea has experience of launching its space rockets down south. It had launched two of its satellites KMS 3-2 and KMS-4 southward (via south pole) into an inclined polar orbit using it's UNHA-3 space launch vehicle. 

Space launch vehicles (SLV’s) need not even be converted into true ICBMs; payloads could be inserted into a low earth orbit (say approx. 200km) and then brought down on their intended targets after orbiting a long way around the planet, similar to the Fractional Orbit Bombardment System (FOBS).

An EMP attack could also be made by a satellite in polar orbit, one which orbits around North & South Poles. A satellite that does nothing would be suspicious, so you’d have to stick a nuclear warhead inside an operational satellite: one that generates enough signal traffic to give a plausible explanation for its existence.

North Korea could make nukes small enough to fit on such satellites which pass over the U.S on a trajectory optimum for an EMP attack. KMS 3-2 and KMS-4 in polar orbits fly over the United States every day at an altitude of 500km which is an optimum height for putting an EMP field over all 48 contiguous states of the U.S

The EMP commission warned that North Korea might even have a super-EMP weapon.

FOBS detection and interception

Early warning satellites can detect and track missile launches from almost anywhere in the world. So the North Korean ICBM launch or FOBS going undetected is highly unlikely. Detection of ICBMs isn’t a problem, but the interception is.

Patriot, Aegis and THAAD ballistic missile defenses aren’t designed to stop ICBMs. They are capable of countering only short, medium and intermediate-range ballistic missiles. The only system capable of defending the United States from a North Korean ICBM attack is the Ground-based Midcourse Defense (GMD) system

There are currently only 44 Ground Based Interceptors (GBI) with 40 located at Fort Greely in Alaska and the remaining 4 missiles at Vandenberg Air Force Base in California emplaced in underground silos.

GMD interceptor missile silo at Fort Greely, Alaska

GMD interceptors have succeeded in destroying the target in 10 out of 18 tests, which gives a 50% kill probability for each individual missile. With that 50% probability, if the U.S shot 4 interceptors at a single threat, it would have a 94 percent chance of taking down the missile (ICBM).

So with a total of 44 interceptors, assuming 4 per target, we can intercept only 44/4 =11 ICBMs.

The GMD interceptors located at Vandenberg AFB (of US west Coast) counter ICBMs launched eastward from Pyongyang, while the North Korean ICBMs launched over the Arctic or the North Pole are countered by the interceptors in Alaska.  North Korea launching ICBMs westward is most unlikely as it is opposite to the direction of the earth’s rotation.

There are no GMD missile interceptors currently facing South, making the Southern U.S largely defenseless against North Korean ICBM’s approaching the United States via the Antarctic or the South Pole. Recently Russia has unveiled once such ICBM called SARMAT which is capable of hitting the U.S via south pole.

However, in the event of a conflict, the two North Korean satellites (assumed to be armed with nukes) would be shotdown by the US Anti-satellite weapon system (ASAT weapon)But we actually don’t know whether the North Korean satellites are armed with nuclear warheads.

“On-orbit” inspection is one method for detecting nuclear weapons in orbit, where the suspect satellites would be subjected to neutron irradiation from an orbiting inspector satellite. Emission of delayed neutrons from the target would reveal the presence of fissionable material. While shielding a nuclear warhead might pose difficulties with inspection in orbit.