Roger Stone, a longtime friend and confidant to Donald Trump, jumped into the fray over Khizr Khan’s scathing criticism of the Republican presidential nominee on Sunday, calling Khan a “Muslim Brotherhood agent.” Khan, the father of slain American war hero Humayun Khan, slammed Trump for his anti-Muslim rhetoric and “schoolyard bullying” in a DNC speech last week. His comments prompted a great deal of praise, but they also triggered a spat between Trump and the Khan family, with Trump questioning why Khan’s wife did not speak during the DNC speech. While Trump’s VP on Sunday apparently engaged in damage control by saying Trump “adores” the Khan family, Stone took to Twitter to write: “Mr. Khan more than an aggrieved father of a Muslim son—he’s Muslim Brotherhood agent helping Hillary.” Stone then linked to a conspiracy theory website claiming Khan’s son was killed not as a hero in Iraq, but as a Muslim on an “Islamist mission” killed before he could complete it. Trump has not yet commented on Stone’s remarks.