Updated Casualty Claims

The Russian News agency TASS claimed on February 28, 2022 that:

Russian troops destroyed 1,146 Ukrainian military infrastructure facilities during their special operation for demilitarizing Ukraine, Russian Defense Ministry Spokesman Major-General Igor Konashenkov said on Monday.

"Since the beginning of the special operation, the Russian Armed Forces have crippled 1,146 Ukrainian military infrastructure facilities, including 31 command and communications centers, 81 S-300, Buk-M1, and Osa surface-to-air missile systems, and also 75 radar stations," the spokesman said.

Operational-tactical aircraft of Russia’s Aerospace Force wiped out six armored columns of the Ukrainian armed forces, the general said.

The Russian combat planes "destroyed 311 tanks and other combat armored vehicles, 42 aircraft and helicopters (including those on the ground), 51 multiple launch rocket systems, 147 field artillery guns and mortars, and 263 special military motor vehicles," the Defense Ministry spokesman said.

Notably, if you take Russia's claims at face value and compare them to estimates of Ukrainian forces before the invasion, this still leaves Ukraine with many functioning military aircraft and tanks. 

Another source has claimed that there have been at least 2000 Ukrainian civilians killed so far in the conflict. 

Ukraine Claims '5,840 Russian Soldiers Killed & 211 Tanks, 862 Armoured Vehicles Destroyed' And 61 helicopters and aircraft.

From this YouTube video from yesterday. These estimates are probably higher than the reality, but there is no doubt that Ukraine has inflicted serious damage on Russian forces.

It is also worth noting that there are almost no reported instances of tank v. tank battles in this conflict so far.