I served as a chaplain at St. Elizabeth's hospital in DC - every few weeks, someone would be admitted for evaluation/treatment because they had tried to enter the White House grounds while carrying a weapon of some sort (ranging from very large Rambo-type knives to guns to explosives). They all had some perceived grievance against the sitting president (at that time Bill Clinton, but those who had served there for many years told me that every president since Eisenhower had had one of these people out to get him). The 'poster boy' for those attempts was, of course John Hinkley, Jr. who had been confined to St. E's after being found not guilty by reason of insanity of the attempt on Ronald Reagan's life, and the wounding of Jim Brady, the press secretary.