The threat of nuclear activity is more real than it has been for decades.
Recently, Trump addressed the United Nations, where he threatened to “totally destroy” North Korea, which he described as being run by “Rocket Man” – yes, this is real life – it’s particularly pertinent to consider the effects of a full-blown nuclear attack.
In light of this, we spoke to Dr Cindy Vestergaard, a Senior Associate at the Stimson Centre in Washington DC, and CDR Ben Cipperley, the U.S. Navy Federal Executive Fellow at the Stimson Centre. We spoke to them about Guam, the community most recently affected by nuclear tests, as well as the potential impacts on Australia.
How likely is it that Guam will be subject to a nuclear attack? How much warning would Guam – and the rest of the world – receive?
It is unclear how likely Guam would be subject to a nuclear attack. While it is the closest US territory to North Korea, it is heavily fortified with air defence missile batteries in South Korea and on Guam, plus an array of Ballistic Missile Defense ships stationed in the Pacific.
If Guam were to be attacked, it would invite an overwhelming response from the U.S. including, but not limited to, options for nuclear retaliation, with support from our Pacific allies. As far as warnings, it is unclear if Kim Jong Un would signal his intent before launching a nuclear strike. The U.S. and our allies have made clear that any strike on the U.S. or our allies will be met with an overwhelming military response so that does not give a large incentive for Kim Jong Un to telegraph a strike.
If North Korea does launch against Guam, satellites may be able to see the missiles on the platform and would definitely be able to detect the launch immediately. If all air defences failed, the time to impact Guam would be approximately 18 minutes.
In its simplest form, what does a nuclear attack in the 21st century look like?
No different than in the 20th century.
Then, as now, the impact depends on the targets (civilian or military, urban or rural), the weather conditions, design and yield of the weapon, and the number of weapons detonated. The immediate effects of the blast and radiation are coupled with the firestorms they create consuming buildings, infrastructure, and vegetation while releasing additional energy many more times than that of the weapon’s yield.
Over the decades, the scale of devastation has increased as cities have grown to be megacities, economies and communications more interlinked alongside the explosive power of modern nuclear weapons today are exponentially greater than the first two detonated over Hiroshima and Nagasaki.
For more specifics on blast, radiation and radioactive fallout, Britannica has a good, not-too-technical overview.
How much space can be affected by one nuclear strike?
This depends on two features; the size of the warhead and how it is designed to explode (ground or airburst), as well as the accuracy of the guidance system.
The September 3rd, 2017 test is estimated to have produced a 100 kiloton yield, but the damage radius is proportional to the cube root of the explosive power so even this improvement in yield does not translate to massive destructive power. Using this calculator, you can see the differences in damage based upon the type of burst (air vs. surface).
Since the missile data for the HS-12 is largely estimated based upon the one (marginally) successful test, it is not clear how accurate the guidance system is. With an estimated circular error probably (CEP) of >5km, one missile may not even hit Guam even if it made it through the gauntlet of air defences. By contrast, the US B61-12 has a CEP estimated at 30m . The counter for this is to launch multiple weapons simultaneously, but I do not have any data on that to make a damage estimate.
Could Australia be subject to similar attacks? How would we be affected?
North Korea has also tested the Hwasong 14 ICBM which is capable of reaching Australia. The HS-14 could travel from North Korea to Sydney in approximately 37 minutes. To Darwin, the missile would make the 6000km trip in approximately 25 minutes.