PARIS, April 26 -- Like something straight out of a spy movie, lots of cloak and dagger was required before AFP could meet three Ukrainian drone manufacturers on the fringes of a hush-hush defence forum in Paris earlier this month.

A rendezvous was set up on a bench near the Champs-Elysees, and a hint of Russian being spoken nearby prompted a quick change of hotel lounge at another interview.

The expertise Ukraine has honed with machines that have transformed the battlefield and left European armies trailing in their technological wake, is highly sought after, with their impact proved again in the Middle East war.

"When I talk to Europeans or Americans, they know very little" about these drones, said Olexandr, an engineer producing Ukr...