DRUZHKIVKA, Ukraine — The Russian Army appears to be massing forces for an attack along the same southern battlefront where Kyiv’s troops are planning one, the Ukrainian military warned on Wednesday.
The warning, by the Operational Southern Command, raised the prospect of a more pitched, seesaw battle in southern Ukraine than had been expected in the Ukrainian counteroffensive, which has been pushing toward the Russian-occupied city of Kherson.
“The enemy continues to wage hostilities along the occupied defense line,” the command said in a statement. The Russians are assembling troops for an assault, it said.
Overall, the front in Russia’s war in Ukraine stretches for more than 1,500 miles in a continuous arc from the city of Kharkiv in the north to the city of Kherson in the south. But it is effectively two distinct theaters of war.
In the eastern Donbas region, Russia has been slowly advancing, while in the southern Kherson region, Ukraine has been recapturing territory with the help of long-range American-provided rockets striking ammunition depots, command posts and bridges deep behind Russian lines.
The strikes on bridges over the Dnipro River, which separates Kherson from Russian supply lines to the occupied peninsula of Crimea, had been seen as particularly hopeful for Kyiv. The Russian Army has begun using barges to cross the river.
But the massing of an assault force in the northern portion of Russia-occupied territory around Kherson would pose challenges to Ukraine’s plans. The Operational Southern Command said Russian troops staged probing attacks with tanks, but did not break through Ukrainian lines.
Russian forces also attacked with helicopters and rocket artillery around Kherson, in an area of flat farmland crisscrossed by small rivers and irrigation canals that form natural barriers, the Ukrainian military said. The Ukrainian Air Force and artillery units struck several Russian targets in the area, it said.
Already in eastern Ukraine, the fighting has settled into a stalemate of Russian advances in some areas and Ukrainian counterattacks in others, with neither side moving more than a few miles over weeks of combat.
The Russian military has turned to its air force to try to break the deadlock, said Serhiy Haidai, the head of the Ukrainian regional administration of Luhansk Province. On Tuesday, Russian planes attacked eight villages and small towns along a front near the administrative border between Luhansk and Donetsk Provinces, he said.
The attacks, Mr. Haidai said, were intended to pin down Ukrainian troops in the east, preventing them from being redeployed to other areas in Ukraine, like the south, where Ukrainian forces are preparing for a counteroffensive.
In the north of Ukraine, Russia attacked the city of Kharkiv early Wednesday morning, launching missiles from across the border near the Russian city of Belgorod, according to a Telegram post by Oleh Synyehubov, the military governor of Kharkiv. There were no immediate reports of casualties.
