Can anything stop a nuclear bomb?

To make matters more difficult, an ICBM can only be intercepted at certain points on its journey: when it launches, when it is out in space, and when it re-enters the atmosphere. Each of these phases “has its limitations”, said LiveScience.

During the launch phase, a country wishing to knock a nuclear bomb off course would have just a few minutes to respond. And countries that have historically been seen as a nuclear threat, such as Russia and China, “have large land masses”. This allows them to “keep their missiles far inland, meaning sea-based interceptors couldn’t get to a missile during its launch phase”.

And any intercepting missile would have to hit exactly the right spot on a nuclear bomb, or it could simply knock the missile off course and towards another, perhaps friendly, country. This is commonly known as the ‘shortfall’ problem. “You really have to be explicit and target the payload at the tip of the missile,” Grego told the site. 

Trying to intercept a missile while it is in its next phase – when out in space – is also extremely difficult. This is because of the so-called “discrimination problem”. In the vacuum of space, where there is very little to no air resistance, it would be all but impossible to figure out which missiles are lighter, decoy missiles, and which are heavy warheads. Intercepting all the missiles to ensure you hit the real warhead might not be possible in such a limited time frame.

Can anything defend against a nuclear attack?

Despite these challenges, the US has spent decades trying to develop a system that could attack a nuclear bomb while it is outside the Earth’s atmosphere. The system is known as the Ground-based Midcourse Defense (GMD). Testing has produced mixed results, but some experts are convinced it could work effectively in an emergency scenario. It is, says Forbes, “the only U.S. military program capable of intercepting North Korean nuclear weapons headed for American soil”.

But GMD has its limitations. Since 1999, it has been tested 18 times, said The Verge, and has failed at least eight of those tests. And, noted the technology website, “the Union of Concerned Scientists argue that these were conducted under artificial conditions where the timing of the incoming missile, for example, was known in advance”.

A study published this year by the American Physical Society has brought the reliability of the system into question. The study, which focused on ICBMs from North Korea, concluded that the GMD couldn’t be relied upon to “counter even a limited nuclear strike” and said that the systems in place were “unlikely to achieve reliability within the next 15 years”.

Article source: https://www.theweek.co.uk/news/defence/957033/can-anything-stop-a-nuclear-bomb