From the Rolling Stone by way of the Huffington Post:
[Ethan] Hawke claimed he witnessed the confrontation backstage at [Willie] Nelson’s tribute concert for his 70th birthday at the Beacon Theatre in New York. The article does not name [Toby] Keith but says it was a country singer who “had a monster hit about bombing America’s enemies back into the stone age.” In 2002, Keith had the song “Courtesy of the Red, White & Blue (The Angry American)” that threatened retribution for the 9/11 attacks.
Hawke said the argument began with [Kieth] telling Kristofferson: “None of that lefty [bullshit] out there tonight, Kris.”
Hawke said Kristofferson then angrily confronted and asked him if he had ever served in the military.
“Have you ever killed another man? Huh? Have you ever taken another man’s life and then cashed the check your country gave you for doing it? No, you have not, so shut the [fuck] up,” Hawke recounted Kristofferson as saying. “You don’t know what the hell you are talking about.”
Damn straight. Only those who have never worn a uniform a day in their life love war.