We cannot allow terrorists to hide in protected enclaves anywhere on earth. It takes only one rogue nation to provide safe haven for them. The world will not be safe from terrorism until all the nations of the world agree to co-operate. Disease Even with the drastic measure of killing healthy livestock, Britain had great difficulty bringing the the hoof and mouth epidemic under control. It would be even more difficult to control a human epidemic.
Airlines allow new diseases to travel around the earth in hours.
When the US Immigration service discovers a person coming into the USA infected with tuberculosis, they immediately put them in strict isolation. The most effective way to control disease is to wipe it out globally. Polio and malaria continue to stalk the planet even though we had the technology to wipe them out decades ago. We made the mistake of leaving pockets of infection to fester. If a dictator took over your country, surely you would want your neighbours to help get rid of him.