回复：回复：1970年：毛泽东在国庆大典对尼克松的一次暗示

It was Robert F Willaims, a black civil rights leader in the U.S. In 1963, Williams asked Mao to speak out on the oppression of Black people in the United States. And in response, Mao issued a Declaration of support for the cause of African-American liberation.
I believe but not sure Mao met Williams at 天安门 in 1966 or 1997 during the height of the cultural revolution. Some expert has to confirm this.