The presence of activism on the sports field dates back decades to the civil rights movement, and should unite athletes in the protest controversy engulfing the American professional sports landscape, according to Sports Illustrated.

“Athletes Are Not Going to ‘Stick to Sports’ and That’s an Admirably American Thing,” is the title of this week’s cover piece. The cover illustration shows professional athletes and National Football League Commissioner Roger Goodell ― all in black and white ― linking arms in front of a red, white and blue backdrop.

Hundreds of athletes and dozens of team owners decided to kneel, sit, link arms or otherwise protest during national anthems across the country at Sunday’s games after President Donald Trump stoked the flames, encouraging team owners to fire a “son a bitch” who disrespects the American flag.

THIS WEEK'S COVER: In a nation divided, the sports world is coming together https://t.co/aONQ0a141s pic.twitter.com/rvuXVmiHq7 — Sports Illustrated (@SInow) September 26, 2017

Sports Illustrated writer Charles Pierce offers several examples of moments when political activism in relation with the national anthem have gotten athletes into trouble, both in the U.S. and around the world. Today’s protests, he wrote, are to be expected because “the inclusion of a national anthem—any national anthem—in a sporting event necessarily politicizes that event.”

The difference, he added, is that today’s protests aren’t directly about the government, but are more about the activity of an entity linked to the government. “The protestors are high-profile African-American athletes raising awareness of how lower-profile African-Americans are often mistreated by police officers.”

Strong, effective messaging, Pierce continued, is bound to make some people uncomfortable. Trump, among other things, says the protests are disrespecting the country. Those who love their country, he added, stay away from NFL games altogether these days. The White House chief of staff chimed in, telling CNN he was appalled by players’ lack of respect. “Every American should stand up and think for three lousy minutes,” John Kelly said.

Yet sports and politics are inherently tied, as HuffPost’s Travis Waldron notes. “The existence of the NFL as a multibillion-dollar business enterprise today is a direct result of its aggressive political engagement ― a tradition that is, in fact, older than the Super Bowl. The league doesn’t stick to sports; why should its players?”