The United States Army’s Rapid Equipping Force (REF) is developing weapons and equipment that will help soldiers in conducting future subterranean operations.

The REF received a request from the 2nd Infantry Division stationed in South Korea in 2012 for equipment that could handle and support combat operations within the complex tunnel environment U.S. soldier would encounter should hostilities break out with North Korea.

After a few years of internal refinement and interim assessments, last February the REF coordinated with the Asymmetric Warfare Group (AWG) and the 307th Brigade Engineer Battalion from the 82nd Airborne Division to test these new systems with a conventional unit.

New equipment that was tested by the paratroopers included breaching equipment like battery-powered circular and chain saws, exothermic cutting torches, specialized optics on their weapons and night vision device enhancement, as well as a breathing apparatus that would allow a soldier to spend an extended period of time in smoke or dust-filled spaces.

Watch the video produced by the REF here:

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Subterranean operations have never been a priority for training for conventional forces, yet the use of tunnels has been a component of warfare since time immemorial. Since ancient times, tunneling has been used to burrow beneath fortifications to weaken a structure or to bypass them entirely. Roman legions had to contend with Jewish rebels in Judea around the year 132 A.C.E. that used a series of interconnected tunnels and caves to conceal fighters and launch guerilla-style attacks. In medieval warfare, tunneling was used to degrade the terrain on which fortifications were built, causing their collapse.

In World War I, allied troops tunneled beneath German lines at the Battle of Messines in Belgium, detonating more than a million pounds of explosives underneath the German positions, killing over 6,000 soldiers almost instantly.

The Japanese in World War II famously used caves and tunnels as defensive positions, often holing up and dying to a man inside their fortifications. On Okinawa, U.S. Marines used a tactic called “blowtorch and corkscrew,” using flamethrowers and gasoline to burn and seal entrances to cave complexes, or explosives to similar effect.

The lasting impression of an invisible enemy appearing and disappearing back into the jungles is an iconic image from the American war in Vietnam, made possible by the North Vietnamese and Viet Cong making adept use of tunnels and caves.

In more recent conflicts, tunnels and caves have been used in Palestine, Afghanistan, Lebanon, and Iraq. As we saw with the dropping of the MOAB last week on an Islamic State tunnel complex, the difficulty and danger associated with conducting subterranean combat makes dropping the largest non-nuclear munitions on it a more appealing alternative.

It is all but guaranteed that U.S. forces will continue to encounter complex subterranean environments in the future, particularly as urbanization in metropolitan centers continues to expand.

Image courtesy of the Times of Israel