JINSA Generals and Admirals Program Participant and Gemunder Center Gaza Conflict Task Force Member on ISIS Terror Tunnels in USA Today

Battle for Mosul Goes Underground
James Thurman and Richard Natonski – USA Today

Battle for Mosul Goes Underground
James Thurman and Richard Natonski – USA Today

The fight against the Islamic State terror group is heading underground. As Iraqi forces, with U.S. support, close in on Mosul, the toughest fighting likely will not be in the streets or door-to-door, but in sophisticated miles-long tunnel networks ISIL has constructed under the city. Fighting in this subterranean domain presents unique tactical, operational, technological and even legal challenges, for which the U.S. military must be better prepared. This is far from the first time tunnels have been used by asymmetric and conventional adversaries, and it is unlikely to be the last.

Tunnel warfare was a crucial part of the Vietnam War, with North Vietnamese forces burrowing underground to transport supplies and launch surprise attacks. Since then, tunneling has become more high tech. The tactics and tools to counter a subterranean foe must also evolve from the “tunnel rats” employed by the U.S. military in Vietnam.

As former commanders of U.S. forces in Iraq and South Korea, we saw modern tunneling firsthand. The North Koreans have dug thousands of storage facilities to evade U.S. and South Korean surveillance. In the past, the North Koreans have also burrowed under the Demilitarized Zone in an attempt to enable surprise attacks on South Korean and U.S. forces stationed there.

Just how effectively tunnels can be used in combat, and how difficult they can be to defeat, became clear in the 2014 conflict between Hamas and Israel. Our appreciation for the threat was heightened by separate trips organized by the Jewish Institute for National Security of America, in which we visited some of these tunnels and the commanders whose units fought in and around them.

Hamas dug numerous “terror tunnels” beneath Gaza and under the border into Israel. These were incredibly sophisticated engineering feats, reinforced with concrete and outfitted with power and communications systems. Some were used for command, control and storing large amounts of weapons and munitions underground, allowing for rapid and undetected movement of launch sites. Some were used to flank Israeli forces, redefining the concept of the front line. Still others were used in attempts to kidnap Israeli civilians, hence “terror” tunnels.

These tunnels undoubtedly posed a challenge for Israel. They complicated efforts to target and destroy Hamas’ rocket and mortar arsenals that threatened Israeli civilians. They also distracted Israeli commanders by substantially increasing the risk of surprise attacks on troops or raids against civilians.

Israel struggled to counter these threats. Aerial reconnaissance and airstrikes were ineffective without technology to map the tunnels’ many branches and exit points. Debris from these airstrikes often made identifying tunnel routes even more difficult. Moreover, many were built directly under heavily populated areas, with entrances in hospitals and other civilian infrastructure. By complicating Israel’s concerted efforts to minimize collateral damage when targeting the tunnels, Hamas adroitly exploited civilian casualties to delegitimize Israel’s campaign. This was both tragic and ironic. Under the law of armed conflict, Hamas was culpable for any injuries befalling civilians it intentionally placed in harm’s way.

Israel’s experiences will provide crucial guidance as America supports Iraqi forces in liberating Mosul. ISIL has controlled the city for more than two years – ample time to prepare for this battle. Coalition forces have already found tunnels in many villages they have cleared on the road to Mosul and elsewhere in Iraq. Similar to Hamas, ISIL has also been attempting to hide behind civilians to further neutralize the coalition’s ability to target the terrorists from the air.

Given the importance of not just defeating ISIL but also winning the hearts and minds of Mosul’s Sunni majority – convincing them they will be kept safe by Iraq’s Shiite-led central government – U.S. military planners almost certainly will exercise caution in using air power against suspected tunnels. That places the onus on intelligence and surveillance capabilities, whether human or technological, to find the tunnels, and it means an even bigger burden on the troops who will have to clear and destroy them.

Taking the fight to ISIL beneath Mosul will not be the job of the U.S. advisers supporting Iraqi troops. But this task very well could fall to U.S. forces in future possible conflicts against conventional or asymmetric opponents. Two Army reports in the past two years have warned that U.S. forces are unprepared to operate in the complex sprawl of modern megacities.

Therefore, it is critical to incorporate lessons from subterranean campaigns such as Gaza and Mosul into our own military planning and combat training centers. Cooperating with allies facing similar threats, like Israel, should be an important part in determining the best tactics, techniques and procedures now and in the future. We must also invest in new technologies to detect, defeat and destroy tunnels.

Our Air Force owns the skies, our Navy, the seas. Our Army and Marine Corps must be prepared to own not just the ground, but also the tunnels beneath it.

Gen. James Thurman, USA (ret.), a 2016 JINSA Generals and Admirals Program participant, is former commander of the United Nations Command, ROK-U.S. Combined Forces Command and U.S. Forces Korea.

Lt. Gen. Richard Natonski, USMC (ret.), a member of the JINSA Gemunder Center Gaza Conflict Task Force, is former commander of the Marine Corps Forces Command.

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