In a video posted on social media in November, the members - all of whom have backgrounds in the US military and intelligence services - urged that military personnel should "refuse illegal orders."
US President Donald Trump called the members "traitors" who should be imprisoned, and said that it was "sedition at the highest level" and "punishable by death."
Trump has deployed the National Guard in American cities in an offensive against illegal immigration and ordered military attacks in Nigeria, Iran and against suspected smuggling ships in the Caribbean and Pacific that have killed at least 130 people.
The attempt to indict the Democrats was rejected on Tuesday by a federal jury, something that is very unusual.
