Hollywood has a long history of playing politics. Stalin understood the importance of the motion picture as a political tool:
"The cinema is not only a vital agitprop device for the education and political indoctrination of the workers, but also a fluent channel through which to reach the minds and shape the desires of people everywhere."
Ayn Rand took part against the communist infiltration of the movie industry. She gave a testimony before the House Un-American Activities Committee on October 20, 1947. Listen to the panel discussion, Ayn Rand, Communism and the Hollywood Blacklist.
I am glad to hear that Pro-war celebrities are making their voices heard and that Martin Sheen faces US backlash.
Related: Check out the Boycott Hollywood Project.