That was the focus of an enormous effort back in the 80s (SDI), but the solutions were not at the time technically feasible. Lots of these technologies for defe

That was the focus of an enormous effort back in the 80s (SDI), but the solutions were not at the time technically feasible. Lots of these technologies for defeating shorter-range missiles are spinoffs of the different approaches explored in the SDI program, but these systems still don't have the performance or cost required to intercept hundreds or thousands of multi-km/s incoming ICBMs and SLBMs within, say, a half-hour window.