@jackmiller just posted about Australia needing Israeli Missile Defence systems like Iron Dome.
@jackmiller/australian-defence-systems-to-iron-dome-or-not-to-iron-dome-1621699829
As it turns out, I'd done some analysis on this issue in 2017 when the North Korean dictator was threatening Australia.
Israel's Arrow III is the world's only fully operation exo-atmospheric hypersonic ballistic missile defence system capable of intercepting nuclear missiles in space and defending an entire country from nuclear attack.
It was designed to defend Israel against Iranian nuclear missiles but has a kill vehicle that is steerable in space and is capable of acting as an anti-satellite weapon and thus also of interception of North Korean long range missiles and many types ICBMs.
It would also be effective against China's nuclear missiles (but not Russian or American as they have too many nuclear missiles and some have extremely high reentry velocities which may be beyond Arrow III's capabilities).
This is analysis from public information about Arrow III’s capabilities to defend Australia from nuclear ICBMs launched from North Korea (or China).
Published data says Arrow III has a slant range of 1500 miles (2414km) and intercepts in space (at least 100km altitude).
It has been said to have anti-satellite capability which would mean it can reach a lot higher than 100km (Most satellites orbit at many thousands of km).
To defend the whole of Israel from an easterly threat (Iran) it must have at least a 250km radius defensive footprint.
If one assumes a min 45 degree angle trajectory and the 2414 km slant range as the hypotenuse of a triangle then the maximum protectible footprint on the ground would be a 1706km radius.
However because such a low angle would cause the missile to travel through more atmosphere so the range would be somewhat less.
Given the much larger quoted slant range and cited anti-sat capability I’ve conservatively assumed a 750km radius prime defensive footprint.
If this is the case a single Arrow III battery could defend the whole East Coast (80% of population) and a 2nd battery could defend Perth, Darwin, Alice Springs & Pine Gap (another 10% of population). See map with suggested locations giving coverage. Red lines are ICBM paths from North Korea to major Australian cities/targets. Aqua circles are 750k prime interception radius and Green circles are 1706 km maximum footprint based on slant range.
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