The fall of the Ukrainian city of Mariupol to the Russians seems inevitable, but it comes up against a group of fighters hidden in the tunnels of a vast industrial complex, a tactical device that many armies have already used.
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It is the apotheosis of urban guerrilla warfare. Fighting in an area of several square kilometers of railway tracks, warehouses, coke ovens, various factories and smokestacks. Reduced visibility, holes, obstacles, traps at every step, steel and concrete as far as the eye can see.
And below, tunnels. Sources evoke more than 20 kilometers of underground corridors, up to 30 meters deep. The information could not be verified by AFP from a reliable source.
The Azovstal metallurgical complex, which belongs to the Metinvest group, controlled by the richest man in Ukraine, Rinat Akhmetov, has been at the heart of the fighting in this city for weeks. So does the Azovmash plant, which manufactures railway equipment, cranes and other heavy metallurgical products.
“How to represent the industrial zone? It’s a city within the city, and there are several underground levels dating from the Soviet period, it’s not possible to bomb from above, you have to clean underground. It will take time,” admitted Eduard Basurin, representative of pro-Russian separatist forces in Donetsk, last week.
For Russian forces, entering the tunnels is “impossible”, confirms Alexander Grinberg, analyst at the Jerusalem Institute for Security and Strategy (JISS). They “can try to do it, but they will be slaughtered because the tunnel defenders have the absolute tactical advantage”.
The previous Stalingrad
The Vietnamese in the Cu Chi tunnels, near Saigon (south), during the Indochina war, the Islamist group Hamas against Israel or the jihadist group Islamic State (IS) in Mosul, at the time of the caliphate, already had them benefited greatly.
But the most striking example dates from the mythical battle of Stalingrad (1942-1943), during the Second World War, with there already intense fighting in an industrial complex, the “Red October” factory.
“The Soviets used the undergrounds, the sewers, the tunnels to go behind the German lines,” a French military official told AFP.
A unit of sappers wreaked havoc in an industrial area of the city. Its commander “discovered an old factory in which German elements were sheltered and managed, from underground, to put three tons of explosives under it to make it collapse” on the enemy.
Even today – and probably for a long time – the tunnels remain very effective in creating uncertainty for the adversary.
They reduce the effectiveness of enemy artillery, airstrikes, infantry, snipers. They impose silence on satellite surveillance and complicate technical intelligence by offering combatants in the lowlands a real ability to move.
But “the network really has to be very dense. They must also have stored ammunition, food and drink. This means a big preparation phase.
water and gases
James Rands, analyst for the private British intelligence institute Janes, evokes for his part the necessary and delicate training of soldiers.
“Closing spaces leads to close-range combat, limiting the effectiveness of certain weapons,” he notes. Explosives increase in power, but the blast effect can backfire.
At the tactical level, “command and control is extremely difficult. Standard communications work poorly and situational awareness is poor as tunnels are generally poorly mapped,” adds James Rands.
Not to mention the hell of medical evacuations. In theory, “one hour of progress in an underground network costs ten hours in the evacuation of victims”, according to him.
But is this underground citadel impregnable? This would require that the Ukrainian forces have a sufficient quantity of all the necessary equipment, such as night vision goggles. And that’s probably not the case.
And they will have to overcome the possible use by the Russians of water, to drown the tunnels and the fighters who are there, or of gas and other chemical products, to make unbearable, even impossible, all life inside.
Can the battle for the industrial zone last? Without explicitly mentioning it, Russian President Vladimir Putin assured Tuesday that the Russian offensive was taking place according to his plans, refusing to set a timetable.
“Our task is to accomplish the set objectives while minimizing losses,” he said.