Retired general: New developments indicate Russia 'has no idea how to sustain a stalled fight' in Ukraine
Pro-Russian separatists ride on top of a tank near the town of Krasnyi Luch in eastern Ukraine, on October 28, 2014 (AFP Photo/Dimitar Dilkoff)

Ret. Lt. Gen. Mark Hertling on Tuesday delivered yet another pessimistic assessment of Russia's military capabilities in Ukraine, and he said that it looked like the country was running out of room to ramp up its abilities to take and hold territory.

Hertling based his analysis of the situation on fresh reporting from DefenseOne Pentagon correspondent Tara Copp, who said that the American military has assessed that Russia's military convoy outside of Kyiv still appears to be "stuck" and that Ukrainian forces "have been able to slow and resist Russian advances."

But what really caught Hertling's eye was Copp's quoting of a Pentagon official who said that "we have reason to believe the Russians are considering their resupply and manning options" for their mission, although there has been no sign of new supply movements in the country.

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"To me, '[Russia] considering their resupply and manning options' translates to '[Russia] has no idea how they will sustained a stalled fight,'" he wrote on Twitter. This [is the] culmination of the offense."

Last week, Hertling argued that the Russian military has taken a shockingly high number of losses in its campaign in Ukraine so far, and he concluded that Russian forces would take a "shellacking" if they ever tried to move directly into Kyiv.