"Great solidarity for our National Anthem and for our Country. Standing with locked arms is good, kneeling is not acceptable. Bad ratings!" the President tweeted Sunday afternoon.
Across the country, dozens of NFL players have been taking a knee during the playing of the national anthem before their Sunday
games. Their protests come as Trump renewed his criticism of athletes taking a knee during the national anthem in protest over perceived social injustices.
On Sunday morning, Trump slammed the league's ratings in a post on Twitter and said again players should be fired or suspended for such protests
-- reiterating remarks he made at a rally in Alabama Friday night.
The President inflamed tensions further Saturday by withdrawing a White House invitation to basketball star Stephen Curry of the Golden State Warriors. Curry had remarked at the Warriors' media day Friday that he doesn't want to attend the White House ceremony scheduled to commemorate the team's championship title.
"'By acting and not going, hopefully that will inspire some change when it comes to what we tolerate in this country and what is accepted and what we turn a blind eye to,'' Curry told reporters. ''It's not just the act of not going. There are things you have to do on the back end to actually push that message into motion."
At the first NFL game Sunday, which took place at London's Wembley Stadium, members of both the Jacksonville Jaguars and Baltimore Ravens took a knee while many other players and coaching staff stood and linked arms. Dozens more players on other teams knelt at their games Sunday afternoon.
Notably, almost the entire Pittsburgh Steelers roster stayed in their locker room during the national anthem.
The NFL announced Sunday morning that it will be dusting off a one-minute ad it produced for the Super Bowl
earlier this year that originally was produced to "demonstrate the power of football to bring people together," the league said.
The league is going to run the ad again
on NBC's "Sunday Night Football" telecast.
In response to Trump's remarks in Alabama, Robert Kraft, of close friend of Trump's and owner of the New England Patriots, issued a statement Sunday morning
saying: "I am deeply disappointed by the tone of the comments made by the President on Friday. I am proud to be associated with so many players who make such tremendous contributions in positively impacting our communities."
NFL players began to kneel during the national anthem last year, when then-San Francisco 49ers quarterback Colin Kaepernick refused to stand
during "The Star-Spangled Banner" before kickoff, sparking both support and backlash.
Kaepernick, who is currently without a team, told NFL Media last August
: "I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color."
On Sunday morning, Treasury Secretary Steve Mnuchin appeared on CNN's State of the Union with Jake Tapper
and said that NFL owners should decide on a rule on how to handle players who kneel in protest during the national anthem.
"The owners should meet and decide on this rule the way they decide on any other rule," Mnuchin said.