“The Great Face-Offs” in the US

Neighboring  countries (Mexico and Canada, along with support of Europe) sign a treaty and send military forces all along US borders on May 6th. Nobody is allowed to exit nor enter the country, and riots ensue in the US. Lots of rushing-out citizens are shot, ramming cars are built to crash through the barricades and international concern grows. The Church of John Brown makes itself known, and sends out private saboteurs to take down the barricades from the outside. The Church was never charged for anything law-wise as they acted smartly enough to remain legally concealed. The newly created organization between countries is now being referred to as the I.D.F. (International Defense Force) and absorbs the GDC.