A foreign policy spokesman for Hillary Clinton's presidential campaign had tough words for Donald Trump during Sunday's presidential debate.

"Go fuck yourself," Jesse Lehrich wrote on Twitter during the contentious debate.

Lehrich, a longtime Democratic operative, was responding to an exchange in which Trump said that he would not have sent American troops into Iraq and that, because of that, Army Capt. Humayun Khan would still be alive.

Khan, a Muslim-American who was killed in Iraq in June 2004, became a centerpiece of the presidential contest this summer after his father spoke at the Democratic National Convention. Clinton has cited the Khan family when going after Trump for what she says are bigoted comments about Muslims.