As commander of U.S. forces in the Middle East, McKenzie has spent the last three years operating in close proximity to the Russians in Syria, and knows their history as one of the world’s great tank armies – all of which has been belied by the first three weeks of war.

“They haven’t been able to maneuver their armor effectively,” McKenzie told CBS News national security correspondent David Martin. “There’s a tremendous history of that, actually, in the Russian military, being able to do deep-armored operations. At the end of the Second World War, they were as good at that as anybody else. But these guys don’t seem to have remembered that.”

“Should heads roll?” Martin asked.

“I would not be happy if that’s the way U.S. forces were performing,” McKenzie replied. “We have non-commissioned officers that are the backbone of the joint force. They’re the people that actually make sure things are done, that continuing actions are taken, that you dig in, that your tanks don’t run out of fuel.”