The NFL said on Friday it will commemorate the 15th anniversary of the Sept. 11 attacks on the United States during games on Sunday, the same day when some players plan to protest during the U.S. national anthem. Four players have so far opted to kneel during the anthem in a protest against social injustice, a controversial gesture that started during the preseason and one that many consider to be a sign of disrespect to the American flag. San Francisco 49ers backup quarterback Colin Kaepernick began protests when he refused to stand for "The Star-Spangled Banner" and others have followed suit, most recently Denver linebacker Brandon Marshall ahead of Thursday's season opener.
