(CNN) -- The buildup of separatist forces in Donetsk, Ukraine, and Moscow's patently confrontational tone are raising the specter of another offensive in eastern Ukraine before winter grips the region. On Wednesday, NATO warned that "columns of Russian equipment, primarily Russian tanks, Russian artillery, Russian air defense systems and Russian combat troops" had been spotted entering Ukraine. Is this crisis about to flare up again, just two months after Russia withdrew its forces? Given the strategic costs, it might seem unlikely that Russia would reignite this war, especially with winter looming. Yet both the opportunity and the motivation appear to be there in Moscow.
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Moscow is striking a patently confrontational tone, says Michael Kofman
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Russian economic woes could impact foreign policy, he writes
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Kofman: Reckless foreign policy risk the new normal in Russia
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If the separatists are sufficiently armed, trained and supported that they can seize territory without the need for Russian regulars, then there is much less for @placeholder to risk.
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Starting another campaign in Ukraine would mean a new spiral of unpredictable events -- yet @placeholder's calculations might be based on a different reading of the situation.