Stories about how governments knew about attacks but just did nothing, have shocked folks for many years, like how they probably knew about the plans to hit Pearl Harbor. People seem to be more convinced of it nowdays, than they were in the 60s when I was told the story.
I was even more shocked as an adult, when I read about the attack on a village in England that the government knew was going to happen. They had deciphered the code from the Enigma machine. But, they didn't want the enemy to know that they had captured the machine; so the decision was made (by Churchill, so the story goes) not to warn the population at all. If they had evacuated, the secret would have been revealed. Oh well, it was for the greater good - they just had no choice.
It was an accumulation of those kinds of stories that kept me from ever believing that there was anything that the government "wouldn't" do. Many years ago i had a conversation with a lady who clerked in the video rental store, about the JFK assassination, and I said that there were many people who might have wanted him out of the way - even vice president Johnson. Well she got all pursed up and said, "I don't believe Mr. Johnson would ever do anything like that." She never had anything to say to me after that!
I thought, Any politician in government would get rid of an obstacle standing in the way of their money/power, as easily as stepping on a cockroach. They do and say and lie and kill people without turning a hair.