US President Barack Obama addresses the 2016 Pacific Islands Conference of Leaders at the East-West Center in Honolulu, Hawaii, August 31, 2016. / AFP PHOTO / SAUL LOEBSAUL LOEB/AFP/Getty Images

— President Obama said San Francisco 49ers quarterback Colin Kaepernick is “exercising his constitutional right” to sit out the U.S. national anthem, but the president acknowledged that the silent protest is a “tough thing” for military service members to accept.

At a news conference in China on Monday, the president said he did not doubt Kaepernick’s sincerity in his decision not to stand for the anthem ahead of the team’s games to protest the treatment of African Americans by law enforcement authorities in U.S. cities. Obama noted a “long history” of sports figures protesting political or social issues.

“There are a lot of ways you can do it,” Obama said after the G-20 Summit here. “As a general matter when it comes to the flag and the national anthem and the meaning that holds for our men and women in uniform and those who fought for us — that is a tough thing for them to get past to then hear what his deeper concerns are. But I don’t doubt his sincerity. I think he cares about some real, legitimate issues that have to be talked about. If nothing else, he’s generated more conversation about issues that have to be talked about.”

Obama said he has not closely followed the controversy surrounding Kaepernick’s actions while he has been overseas, but he said he was aware of the public response, which has been sharply divided. The president has sought to balance his own response to the unrest and mistrust in American cities between African Americans and police officers over the past several years, including in Baton Rouge, La., and Dallas this year.

“You’ve heard me talk in the past about the need for us to have an active citizenry,” Obama said. “Sometimes that’s messy and controversial and gets people angry and frustrated. But I’d rather have young people that are engaged in the argument and trying to think through how they can be part of our democratic process than people just sitting on the sidelines not participating at all. My suspicion is that over time he’s going to refine how he thinks about it. Maybe some of his critics will start seeing that he had a point about concerns about justice and equality. That’s how we move forward.”

Nakamura contributed from Washington.