USA TODAY Sports

After joining San Francisco 49ers quarterback Colin Kaepernick in protest Thursday night, Denver Broncos linebacker Brandon Marshall said his decision to kneel during the national anthem was solely meant to be an expression against social injustices.

"I'm not against the military," Marshall said after the Broncos' 21-20 win against the Carolina Panthers. "I'm not against the police or America. I'm against social injustice."

Marshall said the move was an of solidarity with Kaepernick, his fraternity brother and teammate at the University of Nevada. Kaepernick began his protests in preseason games to bring attention to "racism and police brutality."

Marshall added he would continue not to stand during the national anthem before games, and that he would donate an undisclosed amount to charities supporting his cause. Kaepernick has pledged $1 million to groups combating social inequality.

Broncos coach Gary Kubiak voiced his support for Marshall after the game.

"Brandon is a great kid," Kubiak told reporters. "He is a leader of this team. I believe in my players."

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The Broncos added in a statement: "While we encourage members of our organization to stand during the National Anthem, we understand and respect it being a personal decision."

Marshall becomes the latest player to follow Kaepernick's lead in the protest. Last week, Kaepernick was joined by teammate Eric Reid and Seattle Seahawks cornerback Jeremy Lane in kneeling during the final preseason games.

The Seahawks are planning a pregame “demonstration of unity” that will “honor the country and flag,” wide receiver Doug Baldwin said in a tweet on Thursday. Seattle opens its regular season at home on Sunday against the Miami Dolphins, while the 49ers host the Los Angeles Rams in the second game of a Monday night doubleheader.

“I feel like this is the right platform," Marshall said. "This is our only platform you know, to really be heard, and I feel a lot of times, people want us to just shut up and entertain them, shut up and play football.”