Ukraine’s security service on Tuesday claimed responsibility for killing the head of Russia‘s chemical, radiological and biological weapons unit, Lt. Gen. Igor Kirillov.

An informed source within the Security Service of Ukraine (SBU) told NBC News that the agency was behind the detonation of an explosive device planted in a scooter next to the entrance of an apartment building in Moscow. The Tuesday morning blast killed Kirillov and his assistant, who was not identified by name, according to…