Here are some quotes that might help you understand why Black Americans were against the Vietnamese War.
"No, I am not going 10,000 miles to help murder kill and burn other people to simply help continue the domination of white slavemasters over dark people the world over. This is the day and age when such evil injustice must come to an end."
— Muhammad Ali
“I Ain’t Got No Quarrel With The VietCong… No VietCong Ever Called Me nigger.” — Muhammad Ali, 1966
"If violence is wrong in America, violence is wrong abroad. If it is wrong to be violent defending black women and black children and black babies and black men, then it is wrong for America to draft us, and make us violent abroad in defense of her. And if it is right for America to draft us, and teach us how to be violent in defense of her, then it is right for you and me to do whatever is necessary to defend our own people right here in this country."
— Malcolm X
“Here lies the yellow man, killed by a black man, fighting for the white man, who killed all the red men.” — Malcolm X