 Complete the following phrase:  He was positively impressed with the Jewish Autonomous Republic of Birobidzhan, and participated in the Jewish Anti-Fascist Committee during World War II, co-editing the literary section of the Committees journal, Eynikayt Unity. However, like many Soviet Jewish writers, he became a target of the antisemitic rootless cosmopolitan campaign. Arrested in January 1949, he was tried secretly and executed by a firing squad in the event known as the 