In the 1980s, the U.S. announced an ambition to build a space-based missile shield that could intercept Soviet ICBMS and make nuclear weapons functionally 'obsolete.' It never happened. The technology wasn't there, the costs would have been astronomical and there was always a risk of the Soviets out-scaling the system. After the Cold War ended, U.S. homeland missile defence efforts refocused on rogue and minor actors like North Korea. Now, with the announcement of "Golden Dome', it appears that the U.S. is once again expanding its missile defence ambitions. And so today we look at what's been announced and funded, how it might work, and the brutal economics of complex missile defence.