The recent dissertation on bomber development discussed the program’s requirements (and the cancelled program before that) which made it unambiguously clear the B-21 program’s requirements were explicitly set around a war with China. Range was practically the number one requirement.
Those planes can do a lot of magic when up in the air, but they are vulnerable on the ground and upon take off.
Do you ever wonder how easy it would be for foreign actors within the US to set something up to target the B-21s upon taxi/takeoff?
Maybe something unconventional but effective. Can you think of any countries that purchase land around US military bases?