As fighting intensifies in eastern Ukraine, signs are emerging that Russian President Vladimir Putin has adopted a twin strategy: pledge his willingness to support a negotiated settlement, but continue funneling arms to separatist rebels.

"Putin in the last several weeks has been playing a dual game," said Steven Pifer, a former U.S. ambassador to Ukraine and Brookings Institution senior fellow.

"There have been things that suggest that Russia wants to help solve this diplomatically . . . But you've continued to see evidence that Russians weapons are flowing into Ukraine."