Military intelligence, which is normally enrolled to provide presidential security, stood down.
The FBI stood down.
These elements opened the door to the assassination, but did not have the resources to deliver the shooters and the complicated cover story and witness elimination program that followed.
Corrupt elements of the CIA and their long term friends and colleagues in organized crime did.
And they did it because their very survival was at stake.
After decades of non-investigation by the epically corrupt J. Edgar Hoover, organized crime was on the receiving end of a massive attack by Robert Kennedy - the president's brother and Attorney General.
At the same time, his brother was going after organized crime, JFK was going after the criminal elements that had taken over the CIA.
Few people understand that organized crime and the CIA (and its predecessors) work closely together both inside the US and outside and by the time of the Kennedy assassination had done so for decades. (Watch for our upcoming program "The Curious Case of George White.")
Neither of the Kennedy brothers were choirboys, but what they were undertaking was a heroic effort on their parts and one done for the good of the country. Had they succeeded, they would have averted many of the catastrophes that have befallen the US - and other countries (effecting many hundreds of millions of people) - in the last 49 years
The Kennedy brothers knew the risks involved in their operations. What they attempted required great moral and physical courage the likes of which have rarely been seen in the history of this country.
It's noteworthy that this story, one of the most important in post-war 20th century history, has been completely erased from the public mind and the mass media, through bullshit books (ex. Vincent Bugliosi's latest) and endless snarky gossip pieces designed to diminish President Kennedy's stature.
Note: These are the same group of people who were involved in the wave of US sponsored overseas coups in the 50s and beyond, the same people who set up the military and CIA supported drug operations that supply the US with narcotics from politically approved sources (Iran Contra etc.), and staged 9/11.
Specific operatives have come and gone, but one of the guys who was around for all of these either either on the front lines or behind the scenes: former CIA Director and son of Nazi banker George H.W. Bush.
In case you didn't notice, the reign of his son Bush the Idiot (2000-2008) was completely run by veteran George H.W. Bush operatives.