When the North Korean 11th Army Corps finally marched into battle along the edges of a 250-square-mile salient Ukrainian troops hold in western Russia’s Kursk Oblast last weekend, the long lines of North Korean infantry—striding across open fields in broad daylight—ran headlong into a wall of Ukrainian firepower.

All but one of the assaults ended in bloody defeat, leaving as many as 200 North Koreans dead and wounded out of a total deployed force of around 12,000.

And the assault that did succeed was a Pyrrhic victory for the 11th Army Corps, according to one Ukrainian analysis group. In Plekhove, a village just south of the Psel River on the eastern edge of the salient, a 100-person Ukrainian garrison initially held out against two waves of around 150 North Koreans.

But the attackers kept coming. “The North Korean soldiers went to the assault en masse or, more precisely, in a crowd,” Ukrainian journalist Andriy Tsaplienko reported.

The Ukrainian garrison in Plekhove finally retreated when a third wave of North Koreans attacked from the east.

But the retreat was a calculated one, according to the Ukrainian Center for Defense Strategies. Ukrainian troops “did not cling to Plekhove at any cost, but withdrew north of the Psel River.”

This put an imposing natural barrier between the combined Russian-North Korean force and the main Ukrainian unit in the area, the 61st Mechanized Brigade. “This forces the enemy to cross open terrain to attack positions whose layout is unknown to them, all under strikes from UAVs and artillery,” according to CDS.

Dug in north and west and west of the winding Psel, the Ukrainians have been firing with abandon at the North Koreans and Russians who’ve been struggling to approach the river, cross it and establish a bridgehead in the days since Plekhove fell to the North Koreans.

“Dozens of assaults over the past few days have ended at the distant approaches to Ukrainian defenses,” CDS reported.

The failed attacks have added to Russia and North Korea’s growing tally of losses. In just its first weekend of fighting, the North Korean 11th Army Corps may have lost 4% of its manpower—a rate of loss that’s unsustainable over the long term.

The problem for the Ukrainians is that surrendering any ground in Kursk is risky. Their salient measures roughly 12 miles by 12 miles. The calculated retreat from Plekhove put a five-mile-deep dent in the salient.

The Ukrainians “skillfully uses terrain and maneuver tactics,” CDS crowed. But the Kursk salient offers little terrain—and sparse space to maneuver.

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