The US government is using drones to patrol half of its border with Mexico, a report by the Associated Press says.
The strategy means that the US is increasingly able to move away from using large numbers of border patrol agents along the entire frontier.
The drones allow border control agents to focus on areas of “greater threat”, says the report.
The US border immigration system is under pressure in the face of a worsening border crisis.
According to an investigation by the news agency, there have been about 10,000 drone flights since the new border control strategy began in March 2013.