FOXBORO, Massachusetts — President Donald Trump has picked a fight with the National Football League and it’s one the players seem eager to wage.

Prodded by some incendiary words from Trump, players and coaches around the NFL fought back on Sunday. The New England Patriots were no exception.

Responding to remarks Trump made Friday at a political rally in Alabama, more than a dozen Patriots took a knee during the singing of the national anthem. Other players, including Tom Brady, linked arms in a show of solidarity.

Speaking after a stirring 36-33 comeback win over the Houston Texans, several players said they didn’t take their decision to act lightly. But they were clearly insulted when Trump challenged the NFL’s owners to crack down on player protests during the anthem.

“Wouldn’t you love to see one of these NFL owners, when someone disrespects the flag, to say ‘get that son of a bitch off the field right now. Out! He’s fired,’” Trump said at the rally.

He later told the crowd “if you see it, even if it’s one player, leave the stadium. I guarantee things will stop ... just pick up and leave.”

Trump’s challenge to end that practice and rob players of what they see as their right to protest is supported by many fans, some of whom were at Gillette.

As the Patriots knelt, a significant number of fans began booing and chanting “stand up, stand up.” The players certainly noticed.

“How could you not hear them?” said James White, last year’s Super Bowl hero. “We can agree to disagree. Everybody isn’t going to agree with us. That’s just the way it is.”

Many players said they were shocked by Trump’s invective and interpreted his words as both questioning their character and right to free speech.

“I didn’t believe it. It was like ‘is this a joke?’ Then it sunk in,” said receiver Phillip Dorsett. “Obviously people get angry. People have their opinion but we know what we are. As long as we know what we are and we’re together, those words won’t affect us at all.”

As the national anthem began, a long string of at least a dozen players dropped to one knee. To the right of that group, Brady was among a group of players who locked arms. Brady stood next to Dorsett. “It meant a lot,” Dorsett said. “We’re obviously a team and just him being there means a lot. We’re all one, we’re together, we’re unified.”

Brady said he chose to join the protest to support his fellow NFL players. “You have a lot of respect for the guys who play this sport, not only your teammates but the guys you play against,” he said. “Without them it’s not a great game. I believe in all of us coming together.”

Other players expressed their reasons to act but no one spoke more profoundly than the game’s star, receiver Brandin Cooks. A half hour after catching the winning touchdown pass from Brady, the 23-year-old Cooks said that since both his father and uncle served in the U.S. Marine Corps, his kneeling was no slight to the military.

“A lot of people think we’re disrespecting the flag or the military,” Cooks said. “I have the utmost respect for the men and women that fight for our freedom. Quite frankly, I feel (conflicted) in a sense because I have no courage to be able to do something like that so I understand the magnitude that they’re fighting across the world for our freedom. So that’s not the message that we’re sending. The message we’re trying to send is that we just want respect and unity and there’s only so many ways you can do it.”

As for the boos that later turned to cheers, Cooks said, “I love them. I love my neighbor. That’s what the Lord said to do, right?”

Many of the Patriots fans who chose to boo no doubt felt that this day would never come. For much of the last year, they believed their players wouldn’t drop to their knees like those in other stadiums. That belief spun around the idea that the players wouldn’t act against the wishes of their coach, Bill Belichick. He spent his childhood living near the U.S. Naval Academy and his focus on team and frowning on freelancers is legendary.

Belichick chose not to address the issue afterward but owner Robert Kraft, who owns a cozy relationship with the president, said in a statement that “I am deeply disappointed by the tone of the comments made by the president. I am proud to be associated with so many players who make such tremendous contributions in positively impacting our communities. Their efforts, both on and off the field, help bring people together and make our community stronger.”

Kraft and Belichick have known Trump for many years and socialized and played golf with him. Kraft donated $1 million to the president’s inauguration celebration and also presented him with a Super Bowl LI ring.

Speaking to reporters in New Jersey after a day of NFL player protests around the country, Trump said, “I like Bob very much, we’re friends — he gave me a Super Bowl ring a month ago, right? — so he’s a good friend of mine. I want him to do what he wants to do but we have a great country, we have great people representing our country, especially our soldiers, our first responders, and they should be treated with respect. When you get on your knee and you don’t respect the American flag or the anthem, that’s not being treated with respect.”