The 18-year-old had been under investigation for nearly two years.
The FBI arrested two teenage girls plotting a "mass casualty attack" using pipe bombs and guns targeting Memorial High School in Harris County, Texas, police said.
Russia schemed to send incendiary devices, shipped through a commercial carrier on planes that would potentially end up in the United States, according to sources familiar with the situation.
A Maryland woman who pleaded guilty to a neo-Nazi plot to attack multiple energy substations surrounding Baltimore was sentenced to 18 years in prison.
Coincidentally, Merchant's arraignment came the same day a different man -- 58-year-old Ryan Wesley Routh -- appeared in a Florida court to answer firearm charges connected to an unrelated apparent alleged attempt on Trump's life.
Investigators say that classmate allegedly planned to kill 8 students and a teacher.
