In the war up till now, Russia has enjoyed an asymmetric advantage: It has hit Ukrainian targets with planes and missiles launched from Russia, but Ukraine hasn't fired back, fearing that doing so - that hitting targets inside Russia - would escalate the conflict. With Monday's drone strikes, Ukrainian President Volodymyr Zelensky sent Russian President Vladimir Putin a clear message: From this point on, if you hit us from Russia, I will hit you from Ukraine. 

--SSP alum Fred Kaplan in Slate