KYIV, April 27 - Ukraine’s troops have been forced to make a tactical retreat from three villages in the embattled east, the country’s army chief said Sunday, warning of a worsening battlefield situation as Ukrainian forces wait for much-needed arms from a huge U.S. aid package to reach combat zones.

Col. Gen. Oleksandr Syrskyi reported that Russian forces continue to attack “along the entire front line” of more than 1,000 kilometers (620 miles), with pitched battles raging west of Avdiivka, the eastern city they took in February after a grueling, monthslong fight.

“The most difficult situation is in the Pokrovsk and Kurakhove directions, where fierce battles continue,” Syrskyi’s said in an update posted to the Telegram messaging app, referencing two Ukrainian-held cities in the war-torn Donetsk region, once a hub of industry.

“The enemy has engaged up to four brigades in these directions, is trying to develop an offensive west of Avdiivka and Marinka, making its way to Pokrovsk and Kurakhove,” Syrskyi added. “Units of the Defense Forces of Ukraine, preserving the lives and health of our defenders, moved to new frontiers west of Berdychi, Semenivka and Novomykhailivka.”

Two of these front-line villages lie less than 50 kilometers (31 miles) east of Pokrovsk, while the third is located just over 30 kilometers (19 miles) by road from Kurakhove.

A Washington-based think tank predicted late Saturday that Russian forces “will likely make significant tactical gains in thec coming weeks,” as acute ammunition shortages continue to hobble Ukraine’s defense efforts.

In its latest operational assessment, the Institute for the Study of War said that Moscow’s forces have opportunities to push forward around Avdiivka, and also threaten nearby Chasiv Yar. Its capture would give Russia control of a hilltop from which it can attack other key cities forming the backbone of Ukraine’s eastern defenses.

Despite this, the think tank assessed that neither of these efforts by Moscow are likely to cause Kyiv’s defensive lines to collapse “in the near term.”

The Russian Defense Ministry on Sunday confirmed that Moscow’s troops had taken a village about 15 kilometers (9 miles) north of Avdiivka, days after the war institute reported on its likely capture early on Thursday. That day’s assessment described Moscow’s gains as “relatively quick but still relatively marginal,” adding that Russian troops had advanced by no more than 5 kilometers (3 miles) over the previous week.

U.S. President Joe Biden promised on Wednesday that U.S. weapons shipments would begin making their way into Ukraine within hours, as he signed into law a $95 billion measure — $61 billion of which was allocated for Ukraine — that also included assistance for Israel, Taiwan and other global hot spots. The announcement marked an end to the long, painful battle with Republicans in Congress over urgently needed assistance for Ukraine.

Elsewhere, Russian drones struck the Ukrainian Black Sea city of Mykolaiv early Sunday, setting a hotel ablaze and damaging infrastructure, according to local officials.

Vitaliy Kim, the governor of Ukraine’s southern Mykolaiv province, said that the drones “seriously damaged” a hotel in its namesake capital, sparking a fire that was later extinguished. Kim also reported that the strike damaged heat-generating infrastructure in the city. He added that there were no casualties. (ap/ez)