The U.S. is developing aircraft carrier-based drones that could provide a crucial edge as it tries to counter China's military rise. (AP)

The United States has a near monopoly on armed drones, and it uses the technology aggressively in the hunt for Al Qaeda in Pakistan and Yemen.

But the U.S. could soon lose its edge, as both China and Iran test drones, with groups like Hezbollah and Mexican drug cartels lining up as potential customers.

Security experts have also raised concerns that other countries could follow America's lead, and deploy drones across national borders in the interest of national security.