First the explosion,,,burns off all the oxygen in the blast area
That causes a vacuum...sucks the lungs out of any soldiers still alive.
The best pyrophoric is U238 it burns in air at 6000 degrees and is the perfect density for small maneuvering hypersonic warheads. There is very little in or under the earth that could take a direct hit of 100kg of mass moving at 3+ kilometres per second. Then add in 6000+ degree plasma that continues to burn as long as oxygen OR anything with oxygen in it such as water is present. Humans are 75% water by weight inside a bunker they would be fuel for such a weapon.
The analysis is that the individual sub munitions were in the 100kg mass range. No building on this planet survives a direct hit by a 100kg mass of depleted uranium at mach 10 once that mass reaches the basement and solid ground it will turn to plasma and splash back like a meteor impact sending a 10000+ degree plasma plume up the expanding hole it just punched on the way in anything exposed to the thdermal flux will instantly burst into flames if not vaporize outright. This is identical to what happens to matter exposed to a nuclear fireball’s thermal pulse. Hence is why Russia said it’s like a nuke but not.
You could break up that 100kg sub munition into smaller uranium chunks and kick them out a few kilometers above the target area in expanding cone of plasma death. Even 1 kilogram spikes of U238 kicked out at mach 10 , 2000 meters above a target area would penetrate end to end any civilian structure before the plasma splash on hard ground impact. Maybe a 20+ storey office building might absorb a one kilo mass at mach 10 but every floor penetrated would be wreaked and totally on fire with 6000 degree burning uranium dust in the wake of that penetrator. Kinetic energy weapons have mass area effect potentials. It’s all how much throw weight can you push to mach 10 plus then think this is only a regional weapon ICBMs can push 3 to 10 tonnes to mach 20-27. The secret sauce is being able to guide that mass to a pin point hit and have an alpha value that’s ballistic drag coefficient low enough to keep mach 10+ speeds deep into the atmosphere. Uranium has the density for shockingly high alpha values , tungsten too. Heat shield technology was mastered decades ago. Humans put a probe into jJupiter at 100,000+ mph or mach 100 into gas density much higher than earth’s surface pressure. Long skinny and dense at 15-18 grams per cubic centimeter means you can keep orbital velocity down to the earth’s surface if you enter at a 80 degree angle.