The leader of an armed group stopping undocumented migrants who cross into the United States from Mexico had boasted that his members had trained to assassinate former President Barack Obama and former Secretary of State Hillary Clinton, an FBI agent said in court papers on Monday.

Larry Hopkins was arrested Saturday on a weapons charge. His camouflage-wearing armed United Constitutional Patriots members claim to have helped U.S. officials detain some 5,600 migrants in New Mexico in the last 60 days.

The UCP says its two-month presence at the border is intended to support U.S. Border Patrol, which has been overwhelmed by record numbers of Central American families seeking asylum.