[El Gato]

HMX is a "dual use" substance powerful enough to ignite the fissile material in an atomic bomb and set off a nuclear chain reaction

It doesn't "ignite" it like a conventional fuse or cap ignites chemical explosives. It compresses it, converting a sub-critical mass to a critical mass. (Critical mass depends on geometry and density, as well as isotope ratios and such)

[rebel_yell2]

HMX can be used to ignite fissile material but YOU STILL NEED FISSILE MATERIAL, don't you . . . ?