Chasiv Yar, eastern Ukraine — Ukraine's ammunition starved troops pulled back from two more villages in the country's war-torn east this week, ceding them to Russian forces who've capitalized on their enemies' shortages to seize more territory after taking the hard-fought city of Avdiivka about two weeks ago.

After punishing battles that decimated Bakhmut and then Avdiivka — cities that stood as symbols of Ukrainian resistance for months, even years, but ultimately fell to Russian firepower — Russia's forces have turned their sites and their guns on the nearby city of Chasiv Yar.

CBS News was there months ago, and it was tense even then, but when we returned to Chasiv Yar this week, explosions rang out non-stop and we found a city ravaged by artillery fire, and exhausted troops asking for help.

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We were told to drive at breakneck speed over the crumbling, potholed road leading to Chasiv Yar. At a high point on the road, the trees and houses disappeared and just over the brow of the next hill was Bakhmut, which has been held by Russian forces for months.

We were exposed, and it was a clear day — perfect conditions for drones looking to target vehicles moving in and out of the town.

Russia has been smashing Chasiv Yar with artillery, missiles and airstrikes for months, but Ukrainian soldiers told us the intensity of those attacks spiked over the past few days.

That's one indication the city could be the next target for Russia's grinding offensive in Ukraine's eastern Donbas region. Another is its proximity to Russian-held Bakhmut.

We were supposed to speak with the local commander, but at the last minute we were told he couldn't meet with us; he was directing his forces, who were coming under attack.

With explosions reverberating all around, we passed a bombed-out building onto which someone had spray painted a message: "We are not asking too much, we just need artillery shells and aviation — the rest we'll do ourselves."

It was written in English. Ukraine's forces know exactly who to aim both their dwindling bullets, and their words at.

"We are counting on our American partners to help us with weapons, so that our guys do not have to sacrifice their lives," Reuben Sarukhanian, a soldier with Ukraine's 5th Assault Brigade, told CBS News.

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Russia's lethal reach extends far beyond the battlefield, as residents in the nearby village of Kostyantynivka learned.

As Russian troops advance, countless small towns like Kostyantynivka are in the firing line, and no targets appear to be off limits. The town's historic train station was still smoldering from a Russian missile strike a few nights earlier that turned it into an inferno, and destroyed nearby homes.

It was a direct hit, clearly aimed at crippling Ukraine's civilian infrastructure.

This section of the long front line that stretches right through Ukraine's vast Donbas region has seen some of the worst attacks of the war. It's borne the brunt of two years of blistering offensives and counteroffensives.

But the Russians have the upper hand here now, with more weapons and more manpower — and seemingly no qualms about expending either.

President Volodymyr Zelenskyy was in Albania on Wednesday to co-host a summit aimed at drumming up additional support from Ukraine's European neighbors. But he, and Ukraine's battlefield commanders, know that nothing can replace the $60 billion aid package still stalled in the U.S. Congress.

Without American support, Zelenskyy says, Ukraine will lose.

In:
• United States Congress
• War
• Joe Biden
• Ukraine
• Russia
• Vladimir Putin
• Volodymyr Zelenskyy

Charlie D'Agata

Charlie D'Agata his a CBS News foreign correspondent based in the London bureau.