According to a senior U.S. defense official speaking to Fox News, Russian President Vladimir Putin has deployed 75% of his assembled combat power into Ukraine, but the Russian military's advance to Kyiv has seen little progress in the last day.
Russia has also failed to establish air superiority throughout the country -- all developments that could push Putin to act more aggressive in his campaign, the official said.
"Certainly they have been slowed and they have been frustrated by their lack of progress on Kyiv," the official told Fox News, adding that this could result in a "reevaluation of their tactics and the potential for them to be more aggressive of their targeting of Kyiv."
The official also said that "the Ukrainians are putting up continued and sustained and stiff resistance in and around Kyiv" without any signs of relenting, and have been "very creative" with their tactics.
"They’re using pretty much everything that they have in their arsenal from small arms all the way up to surface-to-air missiles," the official said.
The official also said there's currently no indication that Russia will be deploying reinforcements just yet, adding that there still hasn't been any specific actions from Putin raised his deterrent forces status to "special combat readiness."
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