Complex sentence: In January 1946, Beria resigned as chief of the NKVD while retaining general control over national security matters as Deputy Prime Minister and Curator of the Organs of State Security under Stalin, but the new chief, Sergei Kruglov, was not a Beria man.
Split into simpler sentences: In January 1946, Beria resigned as chief of the NKVD while retaining general control over national security matters as Deputy Prime Minister and Curator of the Organs of State Security under Stalin. But the new chief, Sergei Kruglov, was not a Beria man.