Amazon Prime Air

Amazon’s latest experiment is up in the air — literally.

Amazon chief executive officer Jeff Bezos, who met with President-elect Donald Trump in New York Wednesday, also sent out a rare tweet: “First-ever #AmazonPrimeAir customer delivery is in the books.”

The message marked the trial of service in the U.K. that delivers packages by drone, or unmanned flying robot.

Amazon’s Prime Air is being tested to deliver packages that are up to five pounds in 30 minutes or less, and Amazon completed the first successful delivery Dec. 7.

The first order delivered was an Amazon Fire TV and bag of popcorn, which was sent to a customer near Cambridge, U.K. It took 13 minutes from “customer click” to package delivery.

Amazon is starting small. The first phase of the test includes only two customers and the 30-minute delivery comes at no cost. The e-commerce leader plans to expand this pilot to “dozens” of customers living within “several miles” of its U.K. facility in the next few months, before expanding to “hundreds more.”

A spokeswoman said the rapid parcel delivery service could increase the overall safety and efficiency of the transportation system.

The plan is for customers to be able to order seven days a week during daylight hours, depending on the weather.

One reason that the testing began in the U.K. is because that is where the company was able to reach an agreement with officials. But the company said it would “continue to work with regulators and policymakers in many countries,” and plans to eventually bring Prime Air to customers around the world.

The trial was revealed in July, after Amazon received permission to conduct tests in areas beyond line-of-sight operations in rural and suburban areas.

“Using small drones for the delivery of parcels will improve customer experience, create new jobs in a rapidly growing industry and pioneer new sustainable delivery methods to meet future demand,” said Paul Misener, Amazon’s vice president of global innovation policy and communications when the project began. “The U.K. is charting a path forward for drone technology that will benefit consumers, industry and society.”

Earlier this year, Amazon head of investor relations Darin Manney the company had been working with and developing Prime Air for “some time” to create a rapid delivery system that enhances Amazon’s services, is safe and environmentally sound. “We definitely appreciate the pragmatic and forward-looking approach on this topic with the U.K. and we’re going to continue to work with regulators and policy makers in many countries, including the U.S.”

Bezos was among the tech executives invited to meet with Trump on Wednesday. The specific topics discussed at the meeting were not disclosed. Bezos and Trump had been in discord after the president-elect accused the ceo on Twitter of using The Washington Post, which Bezos owns, as a “tax haven.” While some wondered if Trump would retaliate by hurting Amazon’s e-commerce business, experts said the president-elect’s stated policies would not hurt the web giant.