On the other hand, this is scary

Ok, will someone who understands this stuff please explain to me why I shouldn’t be seriously concerned that the US Army is about to have a brigade stationed in the US?

For more than 100 years -- since the end of the Civil War -- deployment of the U.S. military inside the U.S. has been prohibited under The Posse Comitatus Act (the only exceptions being that the National Guard and Coast Guard are exempted, and use of the military on an emergency ad hoc basis is permitted, such as what happened after Hurricane Katrina). Though there have been some erosions of this prohibition over the last several decades (most perniciously to allow the use of the military to work with law enforcement agencies in the "War on Drugs"), the bright line ban on using the U.S. military as a standing law enforcement force inside the U.S. has been more or less honored -- until now. And as the Army Times notes, once this particular brigade completes its one-year assignment, "expectations are that another, as yet unnamed, active-duty brigade will take over and that the mission will be a permanent one."