The original idea was dubbed "rods from God" and it was proposed by the U.S. Air Force to target bunkers, silos, and other hardened targets without using nuclea

The original idea was dubbed "rods from God" and it was proposed by the U.S. Air Force to target bunkers, silos, and other hardened targets without using nuclear detonations. The rods would have orbital velocity—7 km/s at LEO—giving them, at 10,000kg, about the momentum of a jumbo jet at cruise (an unfortunate comparison, to be sure). Except the kinetic force would be targeted at an area the diameter of a telephone pole, so they would penetrate deeply (100m or more) and cause enough of a shockwave in the earth to collapse almost any buried structure. Their thin profile and solid tungsten construction ensured most of their mass would survive re-entry at close to their original speed. They also evaded the 1967 Outer Space Treaty, which forbade "objects carrying nuclear weapons or any other kinds of weapons of mass destruction"[0]. I'm not sure they actually reach the yield of a nuclear device, but "bunker-buster" nukes are relying on overkill in yield since they can't achieve that kind of ground penetration in delivery. [0] https://history.nasa.gov/1967treaty.html https://history.nasa.gov/1967treaty.html