New Delhi, Aug. 3 -- The improvised explosive device detonated at the entrance of a restaurant on Kudrinskaya Square on Saturday evening, in Moscow's Presnensky District. Three people were killed. Twenty-one others were injured. By Sunday, Mayor Sergey Sobyanin had promised the perpetrators would be found and face the consequences. Russia's National Anti-Terrorism Committee confirmed the device was improvised. Law enforcement agencies, Sobyanin said, were still establishing the full circumstances of the attack.

a detail that matters for what it says about the limits of the security environment around one of Moscow's central districts. Kudrinskaya Square sits in Presnensky, close to one of the capital's Stalinist-era high-rises, well with...