Russia-Ukraine War: Live Updates and Latest News

Jens Stoltenberg, the secretary general of the North Atlantic Treaty Organization, said this week that it was now a “race of logistics” between the two armies and their allies. But in a reflection of the sheer volume of destructive power needed just to hold off the Russians, Mr. Stoltenberg warned that Ukraine’s ammunition expenditure is outpacing Western production.

“This puts our defense industries under strain,” he said.

Artillery is thundering at a furious rate across the entire eastern front — including around Bakhmut, the city in the heart of eastern Ukraine’s mineral-rich Donbas region, where the war’s longest and perhaps bloodiest battle continues to rage.

President Volodymyr Zelensky of Ukraine said the fortitude shown by his soldiers to hold their lines will leave Russia weakened for when Ukraine strikes back.

“Everything that the enemy loses in our Donbas, it will not be able to restore,” he said in his nightly address on Tuesday.

Ukraine is better positioned than it was last summer, when its military warned in late June that it was running out of ammunition as it struggled to hold off a Russian offensive in the east. Then Ukraine was still largely reliant on Soviet-era artillery and weapons systems.

As Western allies stepped up military support, delivering howitzers and precision missiles that helped Ukraine strike deep behind enemy lines, Kyiv halted Russia’s gains and went on the offensive in the northeast and south, scoring some of its biggest gains in the war.

But the intensity of the artillery exchanges is forcing commanders to make difficult decisions about how best to use the stocks they have. On Tuesday, the American defense secretary, Lloyd J. Austin III, said Western nations were pressing for tactical training that could reduce Ukraine’s dependence on artillery fire.

While the United States, Ukraine’s largest supplier of military equipment, has pledged to continue supporting Kyiv, some experts have raised two separate but related concerns: that the war is eating into American military stockpiles that could take years to replenish, and that a slowdown in supplies to Ukraine could give Russia an advantage.

One of the West’s biggest areas of concern is 155-millimeter shells, a key munition in what has become largely a ground-based artillery war. With both Ukrainian and Russian troops firing thousands of howitzer rounds at one another every day, the Pentagon said recently that it would raise its production of artillery shells by 500 percent within two years so that it could eventually produce 90,000 or more shells a month.

An analysis published last month by the Center for Strategic and International Studies, a Washington-based research institute, highlighted that the amount that Ukrainian forces is using every month along the 600-mile front line would eclipse the higher rate of production. That would require other nations to continue providing large amounts of artillery shells, or force Ukraine to reduce its use of them, the analysis said.

“Ukraine will never run out of 155-millimeter ammunition — there will always be some flowing in — but artillery units might have to ration shells and fire at only the highest priority targets,” wrote Mark F. Cancian, a senior adviser at the center. “This would have an adverse battlefield effect.”

Russia, according to Western military analysts, has also severely depleted its conventional weapons stockpile.

Moscow is increasing its military spending, racing to empty its warehouses of ammunition, working to make old equipment ready for combat, and turning to its few military allies, like Iran and North Korea, to strengthen its arsenal, according to an annual threat assessment Norway’s intelligence service published this week.

Russia has used up three-quarters of its modern surface-to-surface missiles in Ukraine, and reserves of older equipment will take time to bring it to the battlefield, the report found.

“Much of this will now be retrieved, but it will take several months to make the material ready for operational efforts,” the assessment said.