Russia has won the Battle of Kursk. Seven months after a Ukrainian force barreled across the border between northern Ukraine and western Russia and occupied a significant salient in Russia’s Kursk Oblast, the Ukrainians have retreated back into Ukraine.

But don’t mistake the Ukrainian retreat as a sign of wider weakness. Elsewhere along the 800-mile front line of Russia’s 37-month wider war on Ukraine, Russian offensives have stalled—or shifted into reverse in the face of determined Ukrainian counterattacks.

Consider what happened on the Siversk axis along the border between Donetsk and Luhansk Oblasts in eastern Ukraine on or before Tuesday. A large Russian force, perhaps from the 3rd Army Corps, attacked the positions of the Ukrainian 30th and 54th Mechanized Brigades and 81st Airmobile Brigade east of Siversk.

With mines, drones and artillery, the Ukrainians made quick work of the long assault column. At least 41 vehicles departed Russian lines that day; as few as 18 returned, many of them damaged. 159 Russians were killed or wounded, according to the Luhansk Operational Tactical Group, which oversees Ukrainian brigades in the area.

Fading fortunes

The wholesale destruction of the Russian assault group is typical of recent clashes in eastern Ukraine. Yearlong Russian offensives around Chasiv Yar, Toretsk and Pokrovsk have all lost momentum as Russian losses exceeded the Kremlin’s capacity to generate fresh troops and vehicles. The Ukrainians are counterattacking in all three sectors, chipping away at territorial gains that cost Russia tens of thousands of troops and thousands of vehicles.

It’s apparent the Russians devoted their best forces to their operation in Kursk—in particular, the elite Rubicon Center of Advanced Unmanned Systems drone group, whose attacks on Ukrainian supply lines in Kursk starting on Feb. 25 precipitated the eventual Ukrainian withdrawal. The concentration of forces in Kursk may have depleted Russian field armies farther south—and afforded Ukrainian brigades the chance to reverse some Russian gains.

The balance of power in eastern Ukraine could shift again. Having won in Kursk, Rubicon may be free to redeploy—perhaps to the east. But the Russians are trying to advance along several axes in the region, and Rubicon can’t cover all of them. It’ll take more than one elite drone group to restore Russian momentum in Ukraine.