Having revolutionized warfare for the United States in the last 15 years, UAVs are going global as the number of countries building and operating them soars.

Until now, such systems have largely been the exclusive purview of the U.S. and a handful of allies. Washington allowed Britain, Italy and Turkey to buy U.S.-built UAVs and operate them usually alongside U.S. forces, but largely rejected requests from other nations keen to acquire the same capability.

But that is quickly changing. U.S. firm General Atomics expects to make its first sales of an unarmed version of its Predator UAVs this year, with Latin America and the Middle East seen to be particularly fertile markets.

“There has been very considerable international interest,” retired U.S. Navy Rear Adm. Christopher Ames, now director of international strategic development for the company, told Reuters at this week’s Farnborough International Airshow.

Flanked by video screens showing the firm’s products in action in Iraq, Afghanistan and tracking pirates over the Indian Ocean, Ames said their combat record spoke for itself.

Not only were human air crew not put at risk, he said, but use of unmanned aerial vehicles (UAVs) also offered huge savings in fuel and personnel costs over conventional manned aircraft.

“The nations that have been operating with us in coalition... have seen what it can do in practice,” he said. “Their conviction goes beyond what marketing hype can provide.”

Privately owned San Diego-based General Atomics was one of the pioneers of early drone technology, operating them first in the Balkans in the 1990s. While the Israeli military has long embraced unmanned aircraft, recruiting specialists directly from model aircraft clubs, other air forces including that of the United States were initially distinctly skeptical.

But the wars that followed the attacks of Sept. 11, 2001, changed all that. In Iraq, Afghanistan, Pakistan, Yemen, Somalia and elsewhere, U.S. forces have become increasingly reliant on UAVs ranging from tiny aircraft operated by infantrymen to those that can fly hundreds or even thousands of miles and stay aloft over 24 hours.