On Sunday, Sept. 24, hundreds of professional football players knelt, sat and locked arms during the United States national anthem before their games began, bringing about mixed reactions across the country.

Players kneeling for the national anthem during football games is nothing new. It started with former San Francisco 49ers quarterback, Colin Kaepernick, who sat at first during the national anthem in 2016, according to the Independent.

Kaepernick explained, in an interview with the NFL media, why he was protesting.

“I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color,” he told the NFL. “To me, this is bigger than football and it would be selfish on my part to look the other way.”

He went on to explain that from his point of view police officers shooting minorities happen far too often but there are hardly any consequences for the officers involved.

Kaepernick switched to kneeling during the national anthem after talking to Nate Boyer, former Seahawks player and Green Beret, according to HBO’s “Real Sports With Bryant Gumbel.”

“We sorta came to a middle ground where he would take a knee alongside his teammates,” Boyer said to Grumbel during an interview. “Soldiers take a knee in front of a fallen brother’s grave, you know, to show respect. When we’re on a patrol, you know, and we go into a security halt, we take a knee, and we pull security.”

According to The Independent, many people have come out for and against Kaepernick’s actions and the actions of those who joined him. For the past year, players within the NFL and other sports have knelt during the national anthem in protest of police brutality against minorities.

For a little over a year this happened, and everything came to a head when President Trump spoke out against their actions at a campaign rally in Huntsville, Alabama, on Sept. 22.

“Wouldn’t you love to see one of these NFL owners,” Trump said, “when somebody disrespects our flag, to say, ‘Get that son of a b**** off the field right now, out. He’s fired. He’s fired!’”

The Washington Post reported that after Trump made those comments, DeMaurice Smith, the executive director of the NFL Players Association, tweeted that they “will never back down when it comes to protecting the constitutional rights of our players as citizens.”

NFL players responded to Trumps criticism en masse.

“In a week, five or eight protesters became in excess of 250,reported Sports Illustrated. Three full teams—Pittsburgh (other than Army veteran Alejandro Villanueva), Seattle and Tennessee—boycotted the anthem Sunday, and other groups either knelt or sat.”

The protests were not against the flag or the military, as some have tried to say they were. The players who knelt made that clear.

“Me taking a knee doesn’t change the fact that I support our military; I’m a patriot and I love my country,” Buffalo Bills Linebacker Lorenzo Alexander said. “But I also recognize there are some social injustices in this country, and today I wanted to take a knee in support of my brothers who have been doing it.”

Not all of the NFL players protested on Sunday. According to Pennlive.com Alejandro Villanueva, the Pittsburgh Steelers offensive tackle and a former Army Ranger, stood alone during the national anthem before the game his team was playing in against the Chicago Bears, Sunday, Sept. 24.

Villanueva is a U.S. military veteran and served in Afghanistan for three years. Pennlive.com reported that he would always stand for the anthem, but he will support those who want to sit or kneel during the anthem. He said he is not offended by those who protest and understands why they kneel.

“What people don’t understand is people that take a knee aren’t saying anything negative about the military; aren’t saying anything negative about the flag,” Villanueva said. “They’re just trying to protest the fact that there’s some injustices in America. For people to stand for the national anthem, it doesn’t mean they don’t believe in these racial injustices. They’re just trying to do the right thing.”