We hear a lot about the technology, impact and ethics of drone strikes flown into Pakistan, but military technology is also moving into unmanned land-based drones and even submarines.

Among the technology being developed is robotic pack horses that can carry hundreds of kilograms of military kit and follow soldiers over any terrain, and hand grenade sized robots that can be thrown into Afghan compounds.

These may sound like sci-fi fantasy, but all were on display at an unmanned drone exhibition in Las Vegas this week.

The BBC's Alastair Leithead reports.