The letter reads:
With great curiosity, I watched the documentary you sent over and found it compelling. Personally, I would like to think we are not alone, and even though I have devoted a generous percentage of my movies to extraterrestrial related themes, I for one have never seen a UFO. That is so unfair! (sic)
I hope you will continue to pursue this topic on your program, and that some day our government will offer a total disclosure about what they know about unidentified flying objects and their true and natural origins.
I continue to enjoy watching you and all your guests.
All my best,
Its no secret Spielberg's fascination with UFOs. The most famous story of course is the screening of E.T. to then president, Ronald Reagan. After watching the movie he turned to the crowd in the room and said "some of you here know that everything on that screen to be true."
In an interview back in 2011 with Ain't It Cool Steven Spielberg confirmed the story to be true but insisted that Reagan was only joking at the time.
Never the less its an interesting letter and shows Spielberg's interest in the subject and his desire for full disclosure.