It didn't make the slightest impression on Hollywood's Communists, but millions were deliberately starved to death by Joseph Stalin in what is known as the Holodomor;
When the winter of 1932 came, it was impossible to leave Ukrainian territory. The soviets had blocked the exits, and there were no supplies or food left to survive on. Joseph Stalin, faced with the possibility of losing Ukraine after the development of his collectivizing agricultural plan, ordered the confiscation of all remaining grain in the country, as well as the obligatory handing over of all means of production to the Soviet state. It was then that famine began.
This is just one of the atrocities that Dalton Trumbo and his Hollywood Ten friends had to ignore while trying to bring a Soviet style of government to the USA (something they didn't even try to hide until the House Committee on Un-American Activities tried to question them about it in 1947).In less than a year, over 7 million individuals were murdered by Stalin. This terrifying statistic was the result of systematic extermination, brought about by communist ideology in Ukrainian territory between 1932 and 1933. It was a mass slaughter that few talk about: the Holodomor (extermination by hunger).
Blacklisting? Too good for them.