In an open letter to Colin Kaepernick criticizing his refusal to stand for the national anthem, former Seattle Seahawk and Green Beret Nate Boyer recalls the time he witnessed genocide in Sudan.

“In 2004, I witnessed genocide firsthand in the Darfur region of Sudan,” he writes in the letter published by the Army Times. “The fact that hate and oppression still exist at that level in our world really hurts me. I met countless young Africans who were enamored with America and the opportunities that exist here. Those people would have given anything to experience what I had grown up with, even just for one day.”

Boyer deployed multiple times to war zones as a Green Beret, including while enrolled at the University of Texas, where he played football for the Longhorns. He was a long snapper, and was later signed as a free agent by the Seahawks for the 2015 season before his release in August.

“I joined the Army upon returning to the U.S. because I believed people like that were worth fighting for,” Boyer continues in the letter. “De Oppresso Liber (‘To Free the Oppressed’) is the Army Special Forces motto, and the reason I wanted to become a Green Beret. I didn’t enlist to fight for what we already have here; I did it because I wanted to fight for what those people didn’t have there: Freedom.”

Boyer spends the opening and ending paragraphs qualifying his criticism of Kaepernick, and affirming the 49ers quarterback’s right to protest in any way he chooses. He explains he didn’t want to add more hate to the furious conversation Kaepernick started, and is listening to what he’s saying. But, he writes the protest “angered” him, and defends the U.S. in its efforts to overcome what racism he acknowledges still remains.

“Overcoming racism at home is a slow process, and we still have a long way to go, but most of us are trying,” he writes. “That’s what sets us apart from so many other places. In this country, no matter who you are, where you come from, what color you are, you can try.”

Speaking of his pride during the one time he got to stand on the sidelines of an NFL game for the national anthem, he adds: “As I ran out of the tunnel with the American flag I could feel myself swelling with pride, and as I stood on the sideline with my hand on my heart as the anthem began, that swelling burst into tears. I thought about how far I’d come and the men I’d fought alongside who didn’t make it back. I thought about those overseas who were risking their lives at that very moment.”

Kaepernick has said he will refuse to stand in support of the flag of a country that “oppresses black people,” and will have another opportunity to continue his protest before a football game Thursday night.

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