Before Russia's invasion of Ukraine, U.S. intelligence had predicted a 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.
Vastly outmatched by Russia's military, in terms of raw numbers and firepower, Ukraine's own air force is still flying and its air defenses are still deemed to be viable - a fact that is baffling military experts.
After the opening salvos of the war on Feb. 24, analysts expected the Russian military to try to immediately destroy Ukraine's air force and air defenses.