Donald Trump sent a strong message to the NFL at a campaign rally in Tulsa, Oklahoma, on Saturday evening, declaring that he and his supporters "will never kneel to our national anthem or our great American flag. We will stand proud and we will stand tall."

In a rally that was pressed ahead by Trump campaign despite warnings that it could impede efforts to contain the spread of COVID-19, president Trump took aim at NFL commissioner Roger Goodell, who last week ago published a video of support for black players and for the 'Black Lives Matter' movement.

"I like Roger Goodell, but I didn't like what he said a week ago. I said 'where did that come from in the middle of the summer?' Nobody's even asking."

The U.S. president recently said he will not watch sporting events if players do not stand for the national anthem.

The issue of kneeling has been a hot topic once again following the death of George Floyd while in police custody in Minneapolis last month.

Several high-profile NFL players including Patrick Mahomes and Michael Thomas created a powerful video that asked the league to condemn racism and admit it was wrong for "silencing our players from peacefully protesting".

New Orleans Saints quarterback Drew Brees apologized after criticizing players who kneel during the anthem, stating he realized the form of protest was "not an issue about the American flag."

Former Former San Francisco 49ers quarterback Colin Kaepernick was the first player to kneel back in 2016 to protest police brutal against African-Americans.