James Cameron Says He Knew Titanic Sub Imploded, Drags Officials for 'False Hope'

James Cameron is putting the U.S. military on blast in the aftermath of the Titanic submersible disaster ... saying he knew right away the vessel imploded, and so did the military -- yet somehow, the search dragged on for days.

The "Titanic" director told CNN it didn't take him long, back on Monday morning, to gather all the facts about the missing OceanGate Titan sub -- saying it immediately had all the markings of something "catastrophic," like an implosion, had occurred on Sunday.

James says he knew it would have to be something like an implosion for the submersible's communications and navigation systems to go out at the same time -- plus, the U.S. military's microphones had picked up a sound right around the same time the sub lost contact.

While he doesn't directly call out the U.S. military ... the fact is, the U.S. Coast Guard was coordinating the search and rescue mission -- an operation James calls a "prolonged nightmarish charade" that did nothing but create "false hope."

As we reported, James also took the opportunity Thursday to point blame at the late OceanGate CEO Stockton Rush, who was the pilot for the fatal voyage ... drawing a grim comparison between the recent trip and the Titanic's tragic one-and-only travel.