There's a new and often overlooked technology available other than conventional bombers. This is kinetic energy weapons launched from space planes or satellites in orbit. They don't use explosive but rely on incredible speeds and their dense mass to penetrate and destroy. Think of a giant GPS guided lawn dart made of depleted Uranium launched at orbital speeeds of around 23000 mph and guided to a target. Add a simple scramjet to make up for the air drag of the atmosphere and you have a pretty formidable weapon that will be very difficult to trace back to the launch point. Originally Posted by SlotgoopThat technology is not "new", by any stretch of the imagination.
Jerry Pournelle has been talking about it for quite literally decades. He called it "Thor", and it occasionally got called "Flying Crowbars from SPAAAACCCEEEE!!!!"
Robert Heinlein described something similar in "The Moon is a Harsh Mistress" in 1966 (Hugo winner, 1967). Lunar colonies revolted, and attacked Earth using big rocks encased in steel, launched from an electromagnetic catapult (today it woudl be called a mass driver). He included first-order calculations of impact energies, and compared them to nuclear weapon effects. (No, I have not checked his numbers, but Heinlein was notorious for doing his homework carefully.)