They won't be.
If the Americans had rushed towards Kiev in the same way the Russians had done, well ahead of supplies, without adequate air support, not protecting their rear and flanks, they would have also suffered high casualties since the Ukrainians were already prepared for their ambushes.
In the Gulf War, the 110,000 strong American Army's VII Corps packing 4 armoured divisions (20,000 men each) was tasked to outflank the Iraqi defences in Kuwait and trap the Republican Guard. The forecast was that they would take 20,000 casualties in the first 5 days of war. They proceeded exceedingly cautiously. Their commander Lt.Gen Frederick Franks even asked for 500,000 hand grenades and 35,000 TOW missiles expecting a melee! The US brought in 220,000 120mm tank rounds to the theatre.
The spearhead of the VII Corps, the 2nd Armoured Cavalry Regiment, 4,200 men strong with 126 M1A1 tanks, 155 Bradley IFVs, 24 155mm self propelled artillery and 50 recon and attack helicopters was expected to easily cover the 120 miles of desert between the Saudi Border and the Republican Guard in 10 hours. Well, that didn't happen. The VII Corps commander was obsessed with synchronising the advance and was terrified of the thought that the US forces might encounter the Iraqis on an empty gas tank so he ordered frequent juice up stops. Each night the entire VII Corps would stop to regain command and control. It took them two days to engage the enemy!
During this gruellingly slow advance, JSTAR ground moving target indicator radar was used to micromanage the 2nd ACR spearhead's advance. However on the day of the engagement, a sand storm degraded the ability of JSTAR to track their movement and GPS was their only means of determining their position. At each successive halt the vehicles would report their front line positions. Because of the storm, no air support to the ground units was possible.
Eventually, the 2nd ACR made contact with the enemy and their training kicked in. They dashed at 25 mph through the Iraqi long range artillery barrage taking out Iraqi scouts, never stopping in their advance. Thanks to the sandstorm, the US forces were ideally situated to take advantage of their thermal sights which could see through the sand and smoke. Firing on the move at high speed, less than half of one squadron, no more than 500 men strong with 19 Abrams tanks and 27 Bradleys, scores of M113s and 12 M109s annihilated an entire Republican Guard 2,500 men strong brigade with 70 T-72 tanks and 70 AFVs, including 32 bunkers of their entrenched positions. 24 hours later, the war was over.
The cost of the slow advance and fear of casualties was that a large portion of the Republican Guard escaped, living to fight another day.
