So I posted this in a few other forums, but I thought that this would be a good place to get even more feedback. Sorry, mods. Does anyone here know what developments are being made in nuclear detection technology? Is there anything like, say, an airborne sensor that can detect the tiniest amount of highly enriched uranium, even if its shielded behind a large amount of lead, in a bustling metropolis like NYC from thousands of feet in the air? Are any developments being made towards that kind of technology?