Telling the truth threatens national security?  More like it threatens the security of the national apparatus which feeds us the big lie and does not want to be called to task for their lies and crimes.

We don't want to tell people the truth - which is that the Gulf problem is huge, will be here for many years to come and will send millions of poeple to early graves so that they can relocate and/or detox and get medical attention.  Far better to cover up the truth, say all is well and let millions suffer and die needlessly than create waves.