I dunno, a 350-kg spike of depleted uranium coming down at terminal velocity is going to do three things:
1. Penetrate deeper than anything we’ve currently got for bunker busting.
2. Create a very large impact crater.
3. Be untraceable.
Yes, those are called “crowbars from G-d,” and probably exist today.
They actually can’t go too fast, as they burn up, so you have air brakes on them.
To get a little extra speed, you put thermal coating (akin to the space shuttle) on them as well, which decreases the mass somewhat.
As an aside, you can do the same thing with an ICBM, which is considerably cheaper — but comes with the issue of following back the arc.