The US’ ground defence system successfully intercepted an ICBM in a simulation — but it may not be enough against a real threat from North Korea

The US put its Ground-based Midcourse Defence (GMD) missile shield to the test in May, firing an intercontinental ballistic missile from the Marshall Islands and knocking it out of the sky with a missile fired from California.

The long-planned test vindicated the expensive, complicated effort to defend the US homeland from missile attacks — but there’s still no stopping a real attack from a determined foe like North Korea.

On Tuesday, North Korea successfully tested a missile that experts say could reach Alaska.