The violence and chaos inside Syria, where Islamic State terrorists and other rebel groups control large portions of the country, is so dire that millions of people have fled and the U.N. has stopped trying to keep count of the dead. Yet Syria is just one of many places across the globe where warlords, separatists, drug cartels, or terror groups have seized territory within a sovereign nation, leaving the government with little or no power—and the people to fend for themselves.