RNA - The FBI said US Army Spc. Jarrett William Smith, 24, who was stationed at Fort Riley in the state of Kansas, had come under investigation in March when authorities learned he had given bomb-making lessons over Facebook.
The name of the news outlet was redacted in the complaint.
Smith, who was charged on Monday, also planned to travel to Ukraine to fight with violent far-right neo-Nazi paramilitary group Azov Battalion.
Court documents portray Smith as a young man who has been active in the far right for years.
He also allegedly suggested targeting Democratic presidential candidate Beto O'Rourke.
"To fight is what I want to do," Smith wrote to an extremist associate, according to an exchange included in the complaint.
The case is the latest in a string of recent arrests and investigations related to attempted far-right extremist infiltration of the US military.
Critics have blamed US President Donald Trump for advocating and promoting white supremacy in the US.US Democratic presidential front runner Joe Biden has accused Trump of fanning the "flames of white supremacy"
Trump's critics point to his rhetoric as a potential source of inspiration for white supremacists abd for inciting violence in American communities.