The battle for Lyman isn’t the biggest or bloodiest in Ukraine as Russia’s wider war on the country grinds through its 43rd month. But it’s still important—and it’s indicative of a bigger problem for outnumbered Ukrainian troops.

The Ukrainian forces in the vicinity of Lyman, a town with a pre-war population of 20,000 that lies just a few miles west of the porous line of contact in northern Donetsk Oblast.

A grouping of around five Russian regiments isn’t making a lot of progress in its repeated efforts to capture Lyman. But that could change.

The town’s defenders, including the 60th and 63rd Mechanized Brigades and adjacent units, have a lot help from the terrain. Specifically, the Zherebets River and connected waterways.

But if the Russians can get across the water obstacles, they could have a clear shot at Lyman—and with heavier forces than the usual foot-borne infantry and motorcycle troops. They could attack with some of the thousands of tanks and other armored fighting vehicles (AFVs) that the Kremlin has been saving up for future offensives in the Ukraine war or other conflicts.

“The only thing that does not allow Russians to attack with AFVs at Lyman direction—river,” reported Kriegsforscher, a Ukrainian marine corps drone operator who has been supporting the defense of Lyman.

To get heavy forces across the waterways, Russian engineers build lightweight pontoon bridges. To prevent the AFVs from crossing, the Ukrainians locate the pontoons with drones—and blow them up with heavier munitions. “We destroy them with the help of aviation and guided bombs,” Kriegsforscher explained.

Cheap bridges

Pontoon bridges are top targets of the Ukrainian air force’s Mikoyan MiG-29 and Sukhoi Su-27 fighters and their American- and French-made precision glide bombs. The jets streak low and fast toward the front line in order to avoid detection by Russian air defenses. A few miles from the front, they climb steeply and release their bombs—and then turn around and speed home.

Arcing high into the air to extend their range, the bombs follow satellite signals to their pre-designated targets. A single 250-kg glide bomb is enough to smash a pontoon bridge. The problem, of course, is that the inexpensive pontoons are easy to replace.

Can the Russians erect pontoon bridges faster than the Ukrainians can locate and destroy them?

If so, the Russians could mass mechanized forces—and make a major push toward Lyman. Kriegsforscher, for one, wrote that he’s worried. “The situation is getting worse.”

Think of the Russians’ Lyman operation as a backup plan. Clearly, their primary plan for laying siege to Kramatorsk and Sloviansk is to roll through Pokrovsk and Kostiantynivka, south of the Kramatorsk-Sloviansk conglomeration.

But that fighting has descended into confusing chaos as more and more Russian and Ukrainian troops shove into a narrow sector and intermingle on a battlefield with no clear front line. If the Russians can’t bring to bear their superior numbers and advance through Pokrovsk and Kostiantynivka, they could shift their main effort north to Lyman.

For the Ukrainians, the Russians’ abundance of options is a major challenge.

Russian forces in the east outnumber Ukrainian forces around three to one. With more troops and heavy equipment, Russian field armies can sustain several major offensive efforts at the same time—shifting resources from one to another if and when conditions warrant.

By contrast, Ukrainian corps lack the same reserves. They must make harder choices about which sectors they strongly defend.

At present, the Ukrainians are going all in on Pokrovsk and, to a lesser extent, on the sector south of Pokrovsk. They’re just barely holding the line around Lyman.

And if the Russians defeat the river, the Ukrainians will lose a key ally around the town.

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