DONETSK REGION, Ukraine (Reuters) - Ukrainian troops trying to hold their ground on the eastern front in Donetsk region may still be outnumbered by Russian forces, but the "shell hunger" that plagued them for months as ammunitions started to run out is now behind them.

One unit in Donetsk region, the focus of Russian troops' slow advance along the 1,000-km (600-mile) front, fired its M-109 self-propelled howitzer as needed -- there were no further fears of running short of Western-supplied 155 mm shells.

"There was 'shell hunger'. Ammunition was rationed quite severely. It had an impact on infantry, they (Russians) crept from all sides, it hurt the infantry men," unit commander Vasyl, 46, told a Reuters TV reporter.

"Now, there is no more 'shell hunger' and we work well."

Demand for 155 mm artillery rounds has soared since Russia invaded Ukraine in February 2022, with Kyiv's Western allies running down their own stockpiles as they rushed shells to Ukraine where thousands of rounds were needed every day.

Now a fresh influx of ammunition has begun arriving at units like Vasyl's after the U.S. Congress ended months of delays and approved a $61 billion aid package.

But for Oleh, 39, a gunner with the unit, other problems remain 28 months in Russia's full-scale invasion.

"There are very few of us. There aren't enough people," he said. "We do not even have half of the people we should have."

Vasyl is more sanguine as he prepares to put the howitzer back into action at a moment's notice, depending on movements of the enemy and its Lancet drones.

"I spot Lancets...and I determine the distance, where it is," Vasyl explains as he readies a heavy machine gun used to down Russian drones carrying munitions.

Convinced that Ukraine will prevail over the Russian invaders, Vasyl is dismissive of Kremlin leader Vladimir Putin's recent diplomatic forays and pledges of cooperation with China and North Korea.

"All these talks with Korea and China, they will not help them, we will win, we shall overcome," he said. "It is our spirit, it is our Ukraine, we are defending it. We shall overcome, at any price but we will win."

(Writing by Ron Popeski; Editing by Michael Perry)

By Anna Voitenko