A Predator drone in Arizona before a surveillance flight near the Mexican border. (John Moore/Getty Images)

Britain is set to buy as many as 26 Certifiable Predator B unmanned aerial vehicles from San Diego-based General Atomics Aeronautical Systems, the Pentagon announced Wednesday.

The $1 billion sale delivers at least 16 of the aircraft, with the option for the country to buy 10 more. The purchase includes the associated material needed to operate the vehicles, including targeting equipment and ground control stations, in addition to contractor support for the aircraft for up to three years.

One of the hallmarks of the U.S. arms sale process, and something that makes it more favorable than some international competitors, is the associated customer support — the inclusion of spare parts and personnel training — that comes with purchasing complicated systems such as drones and fighter aircraft.

“This sale will improve the UK’s ability to meet current and future threats by providing improved Intelligence, Surveillance and Reconnaissance coverage that enhances homeland security, promotes increased battlefield situational awareness, augments combat search and rescue, and provides ground troop support,” the Pentagon said in its news release. The drones “will also be used to support the UK’s armed forces and coalition forces engaged in current and future peacekeeping, peace-enforcing, counter-insurgent, and counterterrorism operations.”

The sale’s announcement coincided with approval by the State Department and notification of Congress.

Britain operates a modest fleet of unmanned aerial vehicles, including the U.S.-made MQ-9 Reaper and Britain’s own Watchkeeper. The British drones often operate alongside their U.S. counterparts and have participated in strikes against the Islamic State in Iraq, Syria and, occasionally, Libya.

The Certifiable Predator B is General Atomics’ upgraded version of the Reaper, boasting a larger wingspan and fuel capacity and a longer loiter time, according to a General Atomics data sheet. The Reaper is capable of staying in the air for a maximum of 27 hours, while the Certifiable Predator B, or CPB, can fly for 40 hours. More fuel and a larger wingspan mean it can carry more ordnance. The Reaper has seven “carriage stores” to hold everything from additional sensors to GPS-guided bombs, while the new CPB has nine.

The CPB sales come a little more than a month after more than 40 countries, including the United States, issued a joint declaration that laid out guidance on the export and use of armed drones.

Although many U.S. allies signed the declaration — including Britain — some countries such as China, Russia, France, Israel and Brazil did not. In recent years, China has slowly entered the global drone market, selling a handful of its armed CH-4 Cai Hong drones to the Iraqi government.

The declaration aims to curb the misuse of armed and surveillance drones, but it’s unclear whether U.S. adversaries will sign on.

The United States, often acting under 15-year-old legal authorities, has in the past year used drones to hit terrorist targets, sometimes accidentally striking civilians, in more than a half-dozen countries.

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