KAZAN, Russia — A string of violent attacks by Islamic militants has shattered this city’s reputation as a citadel of religious tolerance and unnerved federal officials in Moscow, who have worked for decades to prevent the spread of radical Islam out of the southern borderlands and into places like this city 500 miles east of Moscow.

Officials have long sought to contain Islamic fervor in the Caucasus to the south while insisting that places like the republic of Tatarstan, where Kazan is the capital, were different, representing a moderate “Russian Islam,” said Aleksei Malashenko, the co-chairman of the Carnegie Moscow Center’s religion, society and security program.

Read the complete story(Some news sites require registration)