President Donald Trump is once again blasting players who refuse to stand for the national anthem.

Football is back and so is the biggest controversy heading into the new NFL season.

Before a full slate of preseason games Thursday night, players protested during the anthem before kickoff. There were demonstrations in Philadelphia, Miami, Seattle, and Jacksonville.

Dolphins defensive end Robert Quinn raised his right fist during the singing of the national anthem. Malcolm Jenkins of the Eagles also stood with his fist in the air prior to kickoff. Other players around the league went into the locker room before the anthem started.

During the Bills game versus the Panthers, players on both teams stood.

Before Miami’s game, wide receiver Kenny Stills was one of the Dolphins who protested. He and Albert Wilson took a knee behind their teammates.

“If you guys pay attention while I’m on a knee a lot of the time, I’m praying, I thank God for having Albert next to me and being part of this protest hasn't been easy,” Stills told reporters. “I’m grateful he sees what's happening wants to stand up and do something about it as well.”

The player who started the movement to protest police brutality and social injustice, Colin Kaepernick, still does not have a job.

The NFL put the anthem controversy back in headlines earlier this year when it created a new policy requiring players to stand or stay in the locker room during the anthem.

The league responded to the latest protests saying it is still holding talks with the NFL Players Association and the new rules will not be enforced for the time being.

President Donald Trump is once again blasting players who refuse to stand for the national anthem.

Trump claimed on Twitter Friday that "most of them are unable to define" what they're demonstrating against. Instead, Trump tweets players should "Be happy, be cool!"

Trump writes from his New Jersey golf resort that players "make a fortune doing what they love" and that those who refuse to stand "proudly" for the anthem should be suspended without pay.