"There are pressure points. There is some brittleness to the Russian armed forces," Radakin told a small group of reporters in Washington.
But Radakin cautioned that the conflict was slow-moving, with Ukraine poised to take further, incremental advantage of Russian "pressure points." He did not predict any sudden Russian battlefield collapse.
"The underlying feature (of the conflict) is of a grinding nature, with temporary advantages that are seized and built on. You're not seeing a huge shift in balance between the two," he said.
His comments came shortly after Russian President Vladimir Putin on Friday delivered a 37-minute anti-Western diatribe in Moscow before signing documents to annex four regions of Ukraine -- an act denounced as illegal by Ukraine, the United States, the European Union and the head of the United Nations.
Russia controls only parts of the four Ukrainian regions it is annexing.
Even as Putin spoke, his forces 750 km (460 miles) to the south were being encircled in the Ukrainian city of Lyman, and Ukraine said Moscow would have to appeal to Kyiv if it wanted them to be allowed to leave.
Radakin said Putin's remarks, including his renewed nuclear rhetoric, was an example of "Russia responding from a point of weakness and desperation."
"And the rhetoric gets more and more reckless," he said.
Ukraine, which carried out a lightning counteroffensive this month, reclaiming swaths of the Kharkiv region, still had more opportunities in the northeast and in the east of the country, he said. Asked whether Russian mobilization has had any impact on its armed forces in Ukraine, Radakin said: "In a military or a tactical sense, none whatsoever."
"It's revealed the pressure that Russia is under," Radakin said, adding that mobilized Russian forces were being asked to come with bandages and winter gear.
"I don't think that that mobilization, done in such a cack-handed and amateurish and shocking way, instills much fear in the Ukrainian armed forces," he said.
"And if anything, it adds to (Ukraine's) motivation that they're being successful."
(Reporting by Phil Stewart; Editing by Chizu Nomiyama and Jonathan Oatis)
By Phil Stewart
