> The Navy began listening for the Titan almost as soon as the sub lost communications, according to a U.S. defense official. Shortly after its disappearance, the U.S. system detected what it suspected was the sound of an implosion near the debris site discovered Thursday and reported its findings to the commander on site, U.S. defense officials said.
Instead they leaked it once the debris was found?
As for why they revealed their foreknowledge now? I don't speak for the military, but admitting to it vaguely, well after the fact is a significantly different situation than talking about it at the time and making it actionable intelligence. Furthermore, something may have leaked to a journalist, who then pressed them to make some kind of answer.
What conclusions would you draw?