Chinese tests show nuclear bunkers are not what they used to be, with earth-penetrating weapons on the rise

China has built a new research facility to simulate an attack by nuclear bunker-busting weapons and learn how they damage defence facilities, even those built at extreme depths, according to military scientists involved in the project.

In the past, shelters buried several hundred metres deep were rated nuclear-proof but the Chinese test facility shows that a tunnel more than 2km (1.24 miles) under the surface could be destroyed, according to the researchers.