President Donald Trump responded to Sunday's NFL national anthem protests on Twitter.
"Great solidarity for our National Anthem and for our Country. Standing with locked arms is good, kneeling is not acceptable," Trump tweeted. "Bad ratings!"
At least 100 NFL players knelt or sat during the national anthem Sunday after Trump called for the league to fire athletes who participate in anthem protests.
Most teams who played in the early afternoon locked arms in solidarity and at least three team owners joined their players.
The Pittsburgh Steelers stayed inside the locker room as the national anthem played ahead of their game against the Chicago Bears.
The Pittsburgh Steelers said their team will be skipping the national anthem Sunday before their game against the Chicago Bears, according to reports.
Jamie Erdahl of CBS was told by Steelers head coach Mike Tomlin that his team will stay in the locker room during the anthem at Soldier Field in Chicago.
ESPN's Adam Schefter later said he confirmed this with a spokesperson from the team.
The Steelers' actions come after multiple players from both the Baltimore Ravens and Jacksonville Jaguars took a knee during the anthem in London Sunday morning.
A rise is protests was expected after President Donald Trump's comments saying that NFL players who kneel during the anthem should be fired.
Several Miami Dolphins players wore black T-shirts with the words "#IMWITHKAP" on the front during pregame warm-ups Sunday.
Free agent quarterback Colin Kaepernick started the national anthem protests last year.
The NFL only recently spoke out in support of its athletes, after President Donald Trump called for players who kneel during the national anthem to be fired.
Members of the Ravens and Jaguars knelt during the national anthem in the first NFL game since President Donald Trump called for athletes who protest to be fired.
Jaguars owner Shad Khan locked arms with his players in a show of solidarity while former Raven Ray Lewis knelt alongside current Ravens outside linebacker Terrell Suggs and wide receiver Mike Wallace.
President Trump sent two tweets on Sunday morning reiterating his stance on athletes who protest against racial inequality and police brutality during the national anthem. Trump said that change will begin to happen once fans boycott games.
If NFL fans refuse to go to games until players stop disrespecting our Flag & Country, you will see change take place fast. Fire or suspend!— Donald J. Trump (@realDonaldTrump) September 24, 2017
...NFL attendance and ratings are WAY DOWN. Boring games yes, but many stay away because they love our country. League should back U.S.— Donald J. Trump (@realDonaldTrump) September 24, 2017
One of Trump's most staunch supporters, Patriots owner Robert Kraft, released a statement on Sunday morning condemning the president's comments. Kraft said he was "deeply disappointed" and supports his players' "right to peacefully affect social change and raise awareness in a manner that they feel is most impactful."
The president's original comments, which have stirred tension throughout the weekend, occurred during a rally on Friday endorsing Alabama Senator Luther Strange's re-election campaign. In reference to Colin Kaepernick and other protesters in the NFL, Trump said that owners should fire players who kneel during the anthem.
"Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, you'd say, 'Get that son of a bitch off the field right now. Out! He's fired," Trump said.
Jessie Karangu of Sinclair Broadcast Group, Stephen Pimpo Jr. of WJLA and the Associated Press contributed to this report.