LIGHTS OUT for the AirBorne Laser (ABL):

[In] February 2010, the ABL engaged and destroyed its first test target — a solid-rocket fueled Terrier Black Brant rocket. This was followed just more than a week later by another shootdown, this time of a liquid-fueled foreign missile target.

But

Despite finally shooting down its first target, ABL has cratered under the substantial funding required for its work, cost-prohibitive and improbable employment scenarios and, most recently, pressure on the Pentagon budget resulting from growing national debt.

Like many military developments, the technology problems are hard but soluble; the employment problems (getting close enough to fire without being close enough to be fired upon) are harder and sometimes insoluble.