David Kilcullen is one of the world’s leading authorities on insurgencies. For decades he has studied them. As an infantry soldier in the Australian army and an adviser to the U.S. Army, he’s fought against them. His latest scholarly work has focused on their role in urban conflicts.

So when Kilcullen says that America is in a state of “incipient insurgency,” it’s worth sitting up, taking notice, and trembling just a little.

The official definition of an insurgency is the “organized use of subversion and violence to seize, nullify, or challenge political control” of an area. An “incipient insurgency” might be happening when “inchoate actions by a range of groups”—followed by organizing, training, acquisition of resources (including arms), and the buildup of public support—lead to “increasingly frequent” incidents of violence, reflecting “improved organization and forethought.”

Kilcullen argues that this is what we’ve been seeing the past few months in the waves of provocations and street violence that have blown through American cities since the May 25 […]