Before Russia's invasion of Ukraine, U.S. intelligence had predicted a likely blistering assault by Moscow that would quickly mobilize the vast Russian air power that its military assembled in order to dominate Ukraine's skies.
But the first six days have confounded those expectations and instead seen Moscow act far more delicately with its air power, so much so that U.S. officials can't exactly explain what's driving Russia's apparent risk-averse behavior.
"They're not necessarily willing to take high risks with their own aircraft and their own pilots," a senior U.S. defense official said, speaking on condition of anonymity.