Metamaterials that can bend light around an object were first demonstrated nine years ago, and since then many researchers have showed off their own invisibility cloak designs.
The tricky thing is that their invisibility usually only works in the lab from certain angles or at specific wavelengths. The US Army has specified that prototype uniforms submitted must work from all angles, in all terrain and weather conditions, across a wide range of temperatures.
That’s a big ask, especially as any power source required by the camouflage must last at least eight hours and weigh less than half a kilo. But some firms have said that they’re on their way there – most notably a Canadian company called Hyperstealth Biotechnology, which supposedly demonstrated camouflage technology to the US army in 2014.