(CNN) The accounts of Russia's military issues and ineptitude during its three-week-long invasion of Ukraine are too numerous to list.
The proof of Russia's military problems is in a video of Russian tanks, stuck in a line, being destroyed by Ukrainians -- and in reports of Russian combat deaths, which already may be anywhere from 3,000 to more than 10,000.
If those death tolls are toward the higher end -- and we really don't know -- it has been noted that would mean Russian deaths to date could be more than US military combat deaths during 20 years in Iraq and Afghanistan combined, although the total death tolls from those conflicts were far greater than just US military deaths.
There are numerous accounts of Russian soldiers surprised to learn they had been sent to war.
CNN spoke with Russians held as prisoners of war in Ukraine. Nearly a dozen POWs have appeared in news conferences -- public appearances that may be questionable under the Geneva Conventions, which forbid countries from unnecessarily humiliating POWs.
CNN decided to publish interviews with captured Russian pilots. CNN had the only journalists in the room and at no time did Ukrainian Security Services, which also was in the room throughout, interject or direct CNN or the prisoners to ask or answer specific questions. The interview was conducted in Russian.
One, a pilot named Maxim, became emotional with anger and regret at what Russia has done.
"It's not just about demilitarizing Ukraine or the defeat of the Armed Forces of Ukraine, but now cities of peaceful civilians are being destroyed," Maxim said. "Even, I don't know, what can justify, f**k, the tears of a child, or even worse, the deaths of innocent people, children."
There are reports of Russian soldiers who were surprised to learn they had invaded a country rather than taken part in a training exercise. Others have abandoned their posts.
Among the most detailed and engaging analyses cataloging Russia's foibles is an excellent conversation between retired Gen. David Petraeus, who formerly headed the CIA and commanded US forces in the Iraq and Afghanistan wars, and the journalist Peter Bergen. Read it here via CNN Opinion.
Petraeus praised the determination of the Ukrainians: "They are fighting for their national survival, their homeland and their way of life, and they have the home-field advantage, knowing the terrain and communities."
But he also described the Russian army's shortcomings, which begin with the fact that some portion of it -- a quarter, according to one estimate -- is made up of conscripts rather than professional soldiers.
The US, too, has a selective service for all American men in case a draft is ever needed. But while the American draft has been dormant since Vietnam, young Russian men may serve one-year rotations in the military. That's barely enough to get them out of basic training and into a unit, Petraeus said.
The Russians have had problems with intelligence, communications and vehicles getting stuck in traffic jams, stuck in the mud and breaking down.
"So in every single area of evaluation, the Russians, starting with their intelligence assessments and understanding of the battlefield and their adversary, and then every aspect of the campaign, all the way down to small unit operations, have proved woefully inadequate," Petraeus argued.
While they have up to 150,000 troops involved in Ukraine, that's not nearly enough to occupy Kyiv, much less the entire country, he said.
"Failing militaries can be even more dangerous than successful ones," writes Kori Schake, director of foreign and defense policy at the American Enterprise Institute, in The Washington Post.
It is exactly their incompetence that could make this war so devastating, she argues.
"There's reason to worry that the ineptitude and lack of professionalism that Russian forces have displayed in the first three weeks of the conflict are making fighting considerably more brutal for civilians than a more competent military would — and increasing the prospects that the war escalates."
Retired Brig. Gen. Mark Kimmitt was asked Thursday on CNN about the seemingly indiscriminate use of imprecise weapons in civilian areas, something he said must be intentional.
"Their job is to terrorize the population. They're trying to make sure that the cities are shelled, that the people see this kind of shock and they want the city to capitulate. They want to surround it. They want to shell it. They want to starve it, and the Russians then will storm it. This is intentional, and whether these (are) dumb bombs or precision weapons, it doesn't matter."
Photos of a bombed theater housing children seeking refuge in the city of Mariupol, a bombed maternity ward and bombed apartment buildings have renewed calls for war crimes prosecutions. But they are also evidence of desperation on the part of the Russians.
"To me, as a layman, I am not haggling over war crimes because that's clearly what the Russians have resorted to," James Clapper, former director of national intelligence, said Thursday on CNN. "And the reason for it, of course, is the fact they essentially failed in a conventional, tactical attack, so they're resorting to what they can do, which is wanton destruction and the killing of innocent civilians."
Clearly, from the accounts of captured soldiers, this war caught many Russians by surprise. Ukrainians can build that into their defense strategy.
"What Ukrainians need to do is instill fear in the heads of every soldier that around the corner is some civilian or some member of the military who is going to attack them," Evelyn Farkas, a Pentagon official during the Obama administration, said Thursday on CNN.
Petraeus said it was unclear to him how the Russians could rotate their soldiers out of combat roles given their stalled supply lines and their level of commitment.
One indicator may be in a report from the Japanese Ministry of Defense, which told the US it saw Russian ships from the Asian side of the country traveling with combat vehicles, perhaps to reinforce the Ukraine front.