Tornadoes to drop "concrete bombs"

Who'd have imagined laser-guided blocks of concrete?:

[Inert bombs] are basically blocks of concrete shaped as bombs and painted blue to identify them as non-explosive if they are discovered still intact after the war.
[...]
But they will be laser-guided 1,000-lb blocks of concrete, capable of destroying a tank or artillery piece, but without causing a devastating explosion that would put civilians at risk and shatter surrounding buildings.