- Russia doesn't want NATO and Kyiv to believe that arms exports to Ukraine successfully deterred Moscow, said Rob Lee of the Foreign Policy Research Institute.
- "That's why I think that the costs of inaction, from Russia's perspective, are probably greater than the cost of escalating right now," he said.
- When asked how soon Russia could attack, Lee said "it could happen tonight or in the coming days."
From Russia's point of view, it may be better to ramp up aggression on Ukraine instead of doing nothing, according to a senior fellow at the Foreign Policy Research Institute (FPRI).
That's because if Russia backs down now, NATO will think that arms exports to Ukraine were a "key decisive step" and that more deterrence is needed, said Rob Lee of the FPRI's Eurasia program.
Russia doesn't want NATO or Ukraine to believe that's the case, he told CNBC's "Squawk Box Asia" on Monday.
"That's why I think that the costs of inaction, from Russia's perspective, are probably greater than the cost of escalating right now," he said.
Additionally, Kyiv currently has "limited capability" when it comes to long-range missiles, but is working to improve on that.
"One reason why Russia might consider action now to be less costly than waiting is that if Ukraine develops longer-range missile systems, that means any kind of Russian escalation in the future could lead to Ukraine strikes on Russian cities or significant military infrastructure deeper into Russia," Lee said.
Ukraine doesn't have that option right now. "I think that's part of the cost-benefit analysis for them," he said.
When asked how soon Russia could attack, Lee said "it could happen tonight or in the coming days," pointing to signs that Moscow is moving troops and equipment closer to Ukraine, and soldiers are getting into smaller formations.
"Essentially, it looks as though they have just about every piece in place on the military side," he said.
"I think really, it could happen at any moment at this point," he added.
The buildup of Russian troops at the border it shares with Ukraine has sparked fears that Moscow will again invade Ukraine, in a repeat of its annexation of Crimea in 2014. The Kremlin has denied such allegations.