The ongoing war between Russia and Ukraine offers a timely reminder of the fact that underground passageways and facilities can be used in a wide variety of ways by both state and non-state actors, and that this form of warfare isn’t going anywhere. Tunnel detection technology improves every day, yet the appeal of tunnels remains.
Underground warfare in the Russian-Ukrainian war stands out, first and foremost, because it is used by a state (Ukraine). Since 2001, the tactic of subterranean warfare has evolved primarily in the hands of violent non-state groups like Hamas, Al Qaeda, ISIS and Hezbollah. For a state like Ukraine to make use of underground networks is somewhat unusual, if one takes a contemporary view of this old military tactic.
The Ukrainian military is using tunnels and underground facilities that are civilian infrastructure sites, not dug for military use. This enables the Ukrainians to reap the benefits of tunnels without having to dig them. In fact, they have been able to use them to hamper Russia’s offensive, most visibly in Mariupol.
In what constitutes a rather traditional use of the tactic, the Ukrainians are using tunnels to defend against a Russian land invasion. As in Syria, the civilian population was the first to go underground – particularly in subways – to seek protection from the fighting. Fighters later understood that they, too, could make use of this highly strategic terrain.
In the steel underground monster of Azovstal in Mariupol, civilians and fighters cohabited – much like in the infamous and dangerous Vietcong tunnels where women were giving birth. President Vladimir Putin, for his part, operates from major underground command-and-control structures built deep into the earth, which are not so dissimilar from underground American facilities. Ukraine does not have this level of state subterranean capabilities, but its use of the underground similarly attempts to ensure the continuity of its command-and-control structure.
One could argue that Ukraine’s use of tunnels is purely defensive. This could be contrasted with how Israel’s non-state adversaries have dug extensive networks of tunnels as a means to infiltrate Israeli territory, carry out attacks, and counter Israeli capabilities by operating underground.
But such a defensive-offensive take on the tactic would be fallacious. The first core principle of underground warfare could be summed up as such: a tunnel is a tunnel, is a tunnel. Once a tunnel exists or has been dug, it can be used for any purpose.
Hamas in Gaza, for example, used a smuggling tunnel to kidnap Gilad Schalit.
And for years, the US did not fully grasp the security risk posed by drug smuggling tunnels dug on the Mexican side of its border. Yet once a tunnel has been dug, it can be used – simultaneously or not – for smuggling or carrying out terrorist acts.
A second core principle when it comes to tunnel warfare is that every actor will use underground terrain in alignment with their capabilities. Hamas cannot build an enormous Russian-style command and control facility underground. States, therefore, tend to use tunnels differently than non-state actors.
Since 9/11, non-state belligerents have used the underground arena in challenging manners, to reestablish a degree of symmetry in asymmetrical wars.
Fighting sophisticated Western enemies that are better equipped than them has led such actors to go underground, thereby neutralizing intelligence, surveillance, and reconnaissance capabilities. For these types of actors, which include Hamas and Hezbollah, using tunnels evens out the playing field, and that is the reason for underground warfare’s unabating popularity. It serves as the great equalizer in contemporary warfare.
EVEN WHEN two states are at war, as Russia and Ukraine are, those that feel they are at a military disadvantage will fall back on tunnel use to even the field – just as Ukraine has done.
Such tactics deter or slow down Russian advances, and the idea of raiding such tunnels – let alone burning them down – is disheartening. Tunnels will not win Ukraine’s war, but they can help force the Russians to struggle and cause them to lose personnel and time. Tunnels, in this context, are a drain on the attacking force.
History of tunnels
As the Second World War was coming to an end, the Japanese resorted to tunnel warfare against American forces in the Pacific, causing significant losses among US forces and forcing more mobilization of resources.
Decades earlier, in Vietnam, the Vietcong, seeking to embarrass the Americans, attacked them from underground, causing severe casualties and a sense of helplessness. The Americans struggled to deal with this threat coming from below ground, employing B-52 bombers to carpet bomb tunnel-ridden areas.
In war, tunnels create a valuable distraction, offering those who dig them an ephemeral strategic advantage. It is no surprise that ISIS’s last stronghold was a tunnel network in northeastern Syria, or that the late ISIS leader Abu Bakr Al-Baghdadi was eventually found and killed in a tunnel during a US raid on his compound in Syria, in 2019.
Returning to the war that has taken up the world’s attention, Russia knows from fighting the Mujahideen in Afghanistan in the 1980s and the war in Syria that there is no easy way to neutralize subterranean threats.
Russia eliminated ISIS forces hiding in tunnels in Syria using ultra-violent means including the flamethrower, a weapon that burns down the tunnels and anyone inside them. This could not possibly be replicated in the urban jungle of Mariupol.
The use of tunnels in Ukraine reveals that tunnels remain a part of all wars – even between states. States must anticipate future subterranean threats and contemplate how these might differ, depending on the type of actor that uses the tactic and its military capabilities. Though tunnel warfare in Ukraine does not display a high level of innovation, this does not mean that other states will not innovate. Innovation should also come in the form of reclaiming the underground strategic environment. There is no reason why states should not exploit the underground to their advantage.
The third principle is that subterranean threats are here to stay. Technology will not significantly change this in the near future. Pakistan is digging cross-border tunnels into India, according to media reports, despite increasingly powerful Indian tunnel detection technology.
Hezbollah, for its part, has built a disturbingly complex network of tunnels and bunkers in Lebanon. It takes a considerable amount of time to excavate the hard rock, and the likelihood that the digging will be discovered is high. Yet, Hezbollah continues to see tunnels as a key part of its strategy.
On a different scale, China has built underground maritime bases, and Iran is moving parts of its nuclear program underground. It has also built underground missile cities – missile launch bases that are more than 1600 feet down below ground. Those who step up their ability to combine traditional and innovative uses of the underground will be sure to reap the benefits. Anti-tunnel technology has improved but it is unlikely to ever provide a one-size-fits-all solution.
In the meantime, tunnels will continue to exercise their appeal and unabated pull vis-a-vis states and non-states alike.
The writer is a publishing expert at The Miryam Institute.