Quote Originally Posted by HsssH View Post
This is not popular theory, but to me it looked like Clark knew and thats why he asked if JFK wants protection in Dallas.
I think its entirely likely. That he even brought it up suggests to me that on some level he was genuinely thinking about doing something. That there was a strong tug to interfere with time even though he knew he couldn't and in the end didn't. Superman has struggled with this tons of times during his time travel adventures, especially when it comes to the fate of his parents and the like.