Consider the Alternative
I don't understand all the schadenfreude in the comments. If the ABL doesn't work, then the only alternative to a ICBM launch is the promise to nuke Tehran or Pyongyang if they try it. I would like to have an alternative approach that doesn't involve killing millions of people. The trouble with ICBMs is once it is launched it is over. Slower delivery systems gives time for a General or even a guard who doesn't want his family to glow in the dark a chance to give their glorious leader a 9mm lobotomy.
In any case, I don't find the development difficulties the ABL is having as extraordinary. Study the number of failures in the early rocketry program.