"he expects underground fighting to become not merely an add-on issue for the US, and said it might emerge as the primary playing field for combat."
(The US) "would be trying to “drain the swamp” of an adversary’s capabilities in tunnels on foreign soil."
"the US is playing a mostly offensive game on a global field."
"countries do not merely build tunnels. Rather, they build sometimes vast underground facilities under mega cities"
"Maj. Haley Mercer of the US 82nd Airborne Division told the conference that the American military’s doctrine in 2017 shifted from specializing in counterinsurgency warfare to focusing on specializing in subterranean warfare."
"the US is pivoting to using electronic warfare, artificial intelligence and cyber capabilities to use deception and narrative control to confront US adversaries to help shape the “battlefield” in any terrain, before any shots are even fired"
https://www.jpost.com/Opinion/Military-Affairs-The-next-underground-war-611509