The Russian military has largely replaced its heavy battlefield losses in Ukraine, and at a much faster pace than anticipated, said General Christopher Cavoli, the top U.S. commander in Europe, in a written statement to Congress on April 11.
Total estimates of Russia's casualties and equipment losses since the full-scale invasion vary widely.
The BBC's Russian service, along with the Russian independent media outlet Mediazona, confirmed the identities of more than 50,000 Russian soldiers killed in Ukraine earlier in April. The true death toll is thought to be much higher.
According to the General Staff of Ukraine's Armed Forces, Russia has also lost more than 20,000 armored fighting vehicles and tanks, as well as hundreds of planes and helicopters.
Despite this, Cavoli said that Russia has effectively rebuilt its forces.
"The overall message I would give you is (Russia's military has) grown back to what they were before (February 2022)," Cavoli wrote.
"They've got some gaps that have been produced by this war, but their overall capacity is very significant still, and they intend to make it go higher."
Cavoli added that Russia now possesses more frontline troops than it did before the full-scale invasion.
"Russia is reconstituting that force far faster than our initial estimates suggested," Cavoli wrote. "The army is actually now larger — by 15 percent — than it was when it invaded Ukraine."
Russia's military has bolstered its numbers through a partial mobilization conducted in the fall of 2022, which many believe has continued in a more concealed manner since. It has also brought prisoners, migrants, and foreign nationals into its ranks.
The renewed strength of Russia's military is not limited to personnel, Cavoli wrote. Russia now operates as many tanks as it did before the full-scale invasion, he added.
The dire warning comes against the backdrop of a weakening Ukrainian position on the battlefield and a shortage of ammunition, which has been exacerbated by an ongoing impasse in Congress over U.S. aid.
The previous day, Cavoli told Congress that Ukraine will run out of ammunition and air defense interceptor missiles "in fairly short order" without further support from the U.S.
Cavoli said that Russian forces are firing five shells for every one that Ukraine fires — a disparity which he warned could increase to 10 to one in coming weeks — and emphasized the centrality of U.S. aid in Ukraine's ability to defend itself.
"(Ukraine is) really dependent this year on us...and without our support, they will not be able to prevail."