The linked website archives a collection of documents, some of them were formerly secret or confidential, they were all declassified because of the Freedom Of Information Act.

The Freedom of Information Act (F.O.I.A) is an American law that allows members of the public to obtain copies of classified documents by having all or parts of the documents declassified by order of a federal judge. The judge may refuse the declassification of a document if it is necessary for the document to remain classified because it affects national security. At least, that is in theory. In practice it has been very unreliable, if one group requests for a set of documents and gets them, it does not necessarily mean that a second group will be able to get them. If the government denies they have got the documents that you are looking for, they may not be telling the truth. It has been known for a government agency to deny that it has ANY documents on an incident yet release it some months later.

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