The NFL's first full slate of preseason games kicked off last night and there were plenty of eyes on the sidelines as the national anthem played in stadiums across the country. 

Miami Dolphins wide receivers Kenny Stills and Albert Wilson took a knee during the anthem, while teammate Robert Quinn raised his right fist. Others, like Philadelphia Eagles safety Malcolm Jenkins and cornerback Devante Bausby also raised fists ahead of their preseason game against the Pittsburgh Steelers. 

Of course, President Trump was ready to fire off some of his thoughts as soon as those knees hit the turf. In a series of tweets, Trump advised the players to "be happy, be cool" and once again suggested that those who do not stand for the anthem should be suspended without pay.

"The NFL players are at it again - taking a knee when they should be standing proudly for the National Anthem," Trump tweeted. "Numerous players, from different teams, wanted to show their 'outrage' at something that most of them are unable to define."

"They make a fortune doing what they love...Be happy, be cool!" Trump continued. "A football game, that fans are paying soooo much money to watch and enjoy, is no place to protest. Most of that money goes to the players anyway."

"Find another way to protest. Stand proudly for your National Anthem or be Suspended Without Pay!" he added.

The NFL also commented on the demonstration shown by Dolphins players, reiterating that no player can be disciplined for violating any national anthem policy while they continue their discussions with the NFLPA. 

“The NFL has been engaged in constructive discussions with the NFL Players Association regarding the anthem and issues of equality and social justice that are of concern to many Americans,” the statement read. “While those discussions continue, the NFL has agreed to delay implementing or enforcing any club work rules that could result in players being disciplined for their conduct during the performance of the anthem."

The league had previously announced that players would be subject to fines or suspension for not standing during the anthem, but have since backtracked and are now working on a solution.