A giant breathing drone could change the face of modern warfare by hovering over battlefields "indefinitely" secretly monitoring enemy movements.
Some experts believe the Phoenix - which look like a giant bomb - could eventually be perfect for a wide array of military and civilian surveillance uses.
The UK-built drone, which measures 49 feet long and is 34 feet wide, uses a unique “variable-buoyancy propulsion system” to move through the air.
That means as it "breathes" in the air it becomes heavier and then uses its wings to steer forward and into an altitude-losing dive.
It can then release the air enabling it to rise back in the air again eventually up to 20,000ft, reports Popular Mechanics.
The huge drone also has its own supply of helium - or hydrogen- to provide increased buoyancy.
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