Robeson declared that black Americans would refuse to fight for the U.S. if war broke out with the Soviet Union. “It is certainly unthinkable for myself and the Negro people to go to war in the interests of those who have oppressed us for generations,” he said in a speech. The next morning, the headline “Negros Won’t Fight Russia, Robeson Says” appeared in the Los Angeles Times, and the story was picked up in papers worldwide.For several years, racists had been claiming that blacks were welcoming toward communism and lazy during World War II (even though during the war, half a million blacks had served in Europe alone). Many African American leaders objected to Robeson’s statement because it played into both slurs.
(The Red-Baiting of Lena Horne, The Atlantic, AUG 27, 2015)
What does the bold phrase mean? Does "slurs" here mean the two unfair remarks on black people by racists?