United States president Barack Obama has described Colin Kaepernick's decision not stand for the national anthem as "messy" but says he is exercising his constitutional right.
San Francisco 49ers quarterback Kaepernick did not stand for the anthem before his team's third preseason game versus the Green Bay Packers as a form of protest against oppression "of black people and people of colour".
He then knelt during the anthem prior to last Thursday's exhibition with the San Diego Chargers and was joined in doing so by team-mate Eric Reid.
Kaepernick has received both support and criticism for his protest and Obama said in a news conference at the G20 summit: "He's exercising his constitutional right to make a statement.
"I think there is a long history of sports figures doing so. I think there are a lot of ways you can do it when it comes to the flag and national anthem.
"As a general matter, when it comes to the flag, and the national anthem and the meaning that that holds for our men and women in uniform and those that 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 and, if nothing else, what he's done is generated more conversation around some topics that need to be talked about.
"I'd rather have young people who are engaged in the argument and trying to think through how they can be part of our democratic process than people who are just sitting on the sidelines not paying attention at all."