Unmanned Houthi submarines pose new threat to US warships in Red Sea

Unmanned surface and subsurface vessels are likely more difficult to detect and destroy than aerial drones and anti-ship missiles. They are adjusting their strategy, apparently because they haven't been successful in striking a U.S. naval vessel. "If one or more of these weapons get through and kill U.S. sailors, Iran should expect to be held directly responsible" ABC News national security and defense analyst Mick Mulroy, a former Pentagon official and CIA agent, said (Read more at ABCNews).