According to Dr. Kilcullen, there are four environmental “mega- trends” that will be critical in planning future operational strategies. First, the continuing increase in the world’s population in the next generation will change the global landscape. Dr. Kilcullen noted that most studies that record this data predict that the world’s population will accelerate until it reaches around 9.5 billion around the year 2050, meaning that another 3 billion people will arrive before then. Second, the urbanization of that population means that these people will not be evenly distributed over the globe. Based on his research, Dr. Kilcullen believes that around two-thirds of the world’s population will reside in cities, and notably, that population will be aggregated in the developing world. Third, the littoralization (the movement of people from rural, inland areas to the coast) of those densely populated cities will be critical in terms of conflict patterns. Today, around 80 percent of the world’s population lives within 50 miles of the coast and Dr. Kilcullen predicts that this number will only increase. Fourth, and perhaps most significant, the connectivity of the world’s population is rapidly changing, enabling greater access to information and a higher ability to organize among non-state groups.
There's also this interesting quote, too
Dr. Kilcullen noted that since around 1846 until today, the U.S. military has very rarely become involved in state-on-state conflicts. Instead, the United States has engaged with non-state armed group adversaries, a trend completely independent of presidential political preference and one that is growing globally.
I've been saying since 2002 that the excuse of "The US Army doesn't do COIN/small wars/whatever you want to call them" is bunk. We've done it on our own western frontier, in the Philippines (several times), in Central America, in Greece, on the Mexican border, in Africa, all over. Some overt, some not. But to say we "don't do it" because training for a Red invasion of Western Europe is both (a) easier and (b) sexier is ignoring the bulk of US military history.