Michael T. Flynn, a former national security adviser, suggested that a military coup was needed in the United States during a Memorial Day weekend conference organized by adherents of the QAnon conspiracy theory, drawing criticism from political scientists, veterans, Democrats and a handful of prominent Republicans.

Appearing at the “For God & Country Patriot Roundup” conference in Dallas, Mr. Flynn listened to an audience member ask, “I want to know why what happened in Myanmar can’t happen here” — referring to the Myanmar military’s overthrow of a quasi-democratic government and brutal crackdown on dissent, which some QAnon supporters have cited