He had taken responsibility for several attacks on civilian targets since 2009 , including the 2010 Moscow Metro bombings and the 2011 Domodedovo International Airport bombing .
For years , Umarov had been the top terrorist leader in Russia .
Umarov had taken responsibility for several attacks on civilian targets since 2009 , including the 2010 Moscow Metro bombings and the 2011 Domodedovo International Airport bombing .
For years , Umarov had been the top terrorist leader in Russia .