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."
After months of bellicose rhetoric, Putin three weeks ago had Russia's parliament revoke his authority to use Russian military force in Ukraine. Then on Thursday, Putin issued a joint call with German Chancellor Angela Merkel and French President Francois Hollande for a ceasefire in Ukraine.
The cause of Putin's apparent change in tone is the focus of debate in Washington.
Obama administration officials credit American and European sanctions with slowing both Russia's economy and Putin's efforts to sow chaos in eastern Ukraine.
But former U.S. diplomats contend that while two rounds of sanctions have helped, they're not the key factor in blunting Moscow's designs. The successes of Ukraine's new government and failures of its separatists are the primary cause.
"That's first and foremost because of what the Ukrainians are doing," said Michael McFaul, who until February served as the Obama administration's ambassador to Moscow and point man on Russia.
Ukrainian President Petro Poroshenko, elected in May, has done a surprisingly good job of turning Ukraine's military into a more effective fighting force. Ukraine has received $20 million in American military aid, as well as intelligence and advice.
But it is the new government's vetting of troops, decisiveness and willingness to take casualties that have given its military an edge.
At the same time, pro-Russian separatists in eastern Ukraine have done a poor job of generating popular support. Instead of sparking a pro-Russian popular uprising, they have alienated much of the population in eastern Ukraine.