Robert Crews's study of Muslims living under the Tsar indicates that "the mass of Muslims" was loyal to that regime after Catherine, and sided with it over its Ottoman rival.[5] After the Tsarist regime fell, the Soviet Union introduced a policy of state atheism, which impeded the practice of Islam and led to the execution and suppression of various Muslim leaders. Following the collapse of the Soviet Union, Islam regained a prestigious, legally recognized space in Russian politics. More recently, President Putin consolidated this trend, subsidizing the creation of mosques and Islamic education, which he called an "integral part of Russia's cultural code",[6], encouraging immigration from Muslim-majority former Soviet bloc states, and prosecuting what the Russian state considers to be criminal anti-Muslim hate speech, such as caricatures of the Prophet Muhammad.[7]