As Ukraine enters its third day of Russian bombardment following President Vladimir Putin’s invasion this week, a senior defense official said Saturday that Moscow has become “increasingly frustrated” by the lack of momentum.

“We have indications that the Russians are increasingly frustrated by their lack of momentum over the last 24 hours, particularly in the north parts of Ukraine,” the senior defense official said. “We also continue to see indications of viable Ukrainian resistance.”

“We continue to believe, based on what we’ve observed, that this resistance is greater than what the Russians expected,” the official added.