Even with drones already dominating the skies, neutralizing adversaries and covertly collecting data, new research is still underway on the generation of pilotless planes to come.

And the United States isn't the only country interested in developing long-range and lethal drone technology.

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Groups of European and Asian nations — allies and former adversaries alike — are busy investing in next-generation unmanned aerial vehicles of their own.

These UAVs — some in development, some testing, and some already in service — are part of a global competition to gain aerial superiority.

But right now, only a handful of companies are working seriously on this next wave of drones. Some are researching independently, some are working for a single nation, others are working for a dozen.