Today there was a small glimmer of hope from the besieged Syrian city of Aleppo: 12,000 civilians—caught in the crossfire between government forces and rebels—had been evacuated to safety, and the United Nations agreed to send monitors there to ensure their safe passage out of the city.

But then, as evening fell in Turkey, shocking news ripped across the wire: Russian ambassador Andrei Karlov was shot and killed by a gunman while delivering a speech at an art gallery in Ankara. The gunman, wearing a suit and tie, allegedly shouted "Don't forget Aleppo! Don't forget Syria!" as he killed Karlov.

The assassination is a destabilizing event in an already destabilized region, said Charles Sennott, veteran foreign reporter and executive director of The GroundTruth Project.

"This couldn't be at a worse time in terms of what this could mean for the region," Sennott said.

"This is a fragile balancing act right now, to try to bring Russia together in a fight against ISIS. There is a nightmare unfolding in Aleppo as we've all been watching, and now a little glimmer of hope as they begin to try to bring some of the refugees out. To call it a tinderbox is to put it mildly," he continued.

The Russian Foreign Ministry later declared the assassination an act of terrorism, raising questions about how—if at all—the incident could impact Russia's involvement in Syria. As reported by NPR, Russia is a close ally of Syria's regime and is "involved in a wide-ranging airstrike campaign" there. Russian President Vladimir Putin said he believed the killing was a "provocation aimed at derailing Russian-Turkish ties and the peace process in Syria."

"I can't think of a worse time for this assassination to happen. It's clearly premeditated in the sense of trying to add fuel to a situation that's already on fire," Sennott said.

To hear more from Charles Sennott, tune in to Boston Public Radio above.