Subterranean operations involving the use of tunnels and underground facilities pose growing challenges to the U.S. military, a new Army manual indicates.

“Today, over 10,000 known subterranean facilities exist around the world,” the manual says.

“Whether to protect vital assets and capabilities, mitigate weapon system and sensor overmatch, to strengthen a larger defensive position, or simply to be used for transportation in our largest cities, subterranean systems continue to be expanded and relied upon throughout the world. Therefore, our Soldiers and leaders must be prepared to fight and win in this environment.”

See Subterranean Operations, Army Techniques Publication ATP 3-21.51, November 2019.

Logistical issues aside, subterranean operations can have adverse effects on soldiers’ emotional, moral, and spiritual health, the Army manual said.

“Subterranean environments may reduce a Soldier’s sense of purpose and commitment, causing them to lose combat effectiveness sooner than anticipated due to the psychological and physiological stress of these environments.”

“As a result, Soldiers may have powerful emotional reactions. These may include an overwhelming sense of fear or momentary loss of their moral compass leading to illegal or immoral actions.”