A declassified but restricted access intelligence report provided to Congress estimates the Russian Army has lost 87 percent of its pre-Ukrraine invasion strength on the battlefield.

Since the beginning of the war Russia has suffered from a staggeringly high number of losses, according to another newly declassified assessment shared with Congress. At the start of the war the Russian army stood at 360,000 troops. Russia has lost 315,000 of those troops, forcing them to recruit and mobilize new recruits and convicts from their prison system.

Moscow’s equipment has also been crushed, according to the assessment. At the start of the war, Russia had 3,500 tanks but has lost 2,200, forcing them to pull 50 year old T-62 tanks from storage.

To be clear, the Russian Armed Forces numbered about 900,000 personnel in all the military services and the paramilitary Rosgvardiya. The 360,000 number reflects the total active duty strength of the Russian Army. 

When one considers that the Russian Army that invaded Ukraine numbered about 190,000, the level of wastage is more evident.

The same report estimates that 2,200 of 3,500 modern(ish) tanks and 4,400 of 13,600 infantry fighting vehicles have been destroyed. Like any other assessment, it isn't precise. For instance, the tank number is an underestimate. The site Oryx, which counted, geolocated, and documented lost vehicles and equipment seen in photos and video, cataloged 1,690 destroyed, 191 abandoned, and 546 captured Russian tanks before it closed its doors in October.

Context when evaluating casualties is important. Let's look at the 36th Infantry Division's attempt to force a crossing of the Rapido River from January 20 to 22, 1944. The two-day battle cost the 36th 2,128 casualties: 155 killed, 1.052 wounded, and 921 missing and captured. Two of the three infantry regiments participated in the attack, about 6,000 men. So, on the one hand, the division, which had a strength of about 12,000 men, suffered 16 percent casualties, but the two infantry regiments had 33 percent losses. The fighting was done at the company level. Each infantry regiment had 12 companies of about 190 men (I'm being generous as this is 100 percent strength), meaning that 4,500 men were involved in the attack. The 2,100 casualties represent a minimum of 50 percent losses, meaning the two assault regiments ceased to exist as a combat force.

The impact on the Russian Army goes far beyond the raw numbers. The losses reflect a genocide among Russia's pre-war combat units. The 315,000 estimated casualties are 165 percent of the number of troops that crossed the border on February 24, 2022. Suppose you assume that 70 percent of the Russian Army is assigned to combat units (a number that I'd put on the improbably high side of the spectrum). In that case, the estimated losses represent 142 percent of the combat soldiers in the Russian Army in 2022.

Initial losses in Ukraine drew in trained ground troops from all over Russia after the invasion force had been decimated. These replacement forces were gradually expended, too. The upshot of these losses explains much of the video we see of the Russian Army in action. There is no coordination of armor, infantry, and artillery. There is no attempt at maneuver. 

There was an upstream impact as Russian soldiers manning training facilities were sent into combat, and inexperienced reservists filled their places recalled to active duty. The effect is that the Russian Army isn't learning from its experience in Ukraine because the demand for manpower prevents sending experienced soldiers back to Russia to train conscripts.

While Russia might, arguably, be able to keep pace with the losses without resorting to national mobilization, nothing is going to change the fact that the troops going to Ukraine will be exponentially less trained and experienced than those in the invasion force, and their equipment will be much older and less reliable.