The Trump administration’s recent announcement of a “Golden Dome” strategic missile defence shield to protect the US is the most ambitious such project since President Ronald Reagan’s Strategic Defense Initiative (SDI) of the 1980s.

The SDI programme – better known by its somewhat mocking nickname of “Star Wars” – sparked a heated debate over its technical feasibility. Ultimately, it would never become operational. But do we now have the technologies to realise the Golden Dome shield – or is this initiative similarly destined to be shelved?

A completed Golden Dome missile defence shield would supposedly defend the US against the full spectrum of air and missile threats, including long-range intercontinental ballistic missiles (ICBMs) and those with shorter ranges – any of which could be armed with nuclear warheads.

But Golden Dome would also aim to work against cruise missiles and hypersonic weapons such as boost-glide vehicles, which use a rocket to reach hypersonic speeds (more than five times the speed of sound) before continuing their trajectory unpowered.

The missile defence shield could theoretically also protect against warheads placed in space that can be commanded to re-enter the atmosphere and destroy targets on Earth – known as fractional orbital bombardment systems.

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