The idea of Amazon drones delivering small packages within 30 minutes has been around since last year, and some people may believe it’s just a futuristic dream that will never happen. Amazon sees the delivery service as a very realistic goal, and they continue taking necessary steps to make drones a reality.

But problems have arose between the online giant and the Federal Aviation Authority (FAA). Current FAA rules prohibit the use of commercial drones in the U.S. Companies aren’t even allowed to perform flight tests, which Amazon must do. New FAA laws that will go into effect early next year could have even more restrictions.

According to The Wall Street Journal, Paul Misener, Amazon’s vice president of global public policy, sent a letter to the FAA concerning the Amazon drone research and restrictions. “I fear the FAA may be questioning the fundamental benefits of keeping [drone] technology innovation in the United States,” Misener said.

Misener continued, warning the FAA that if their regulations on altitudes for drones don’t loosen, they will be forced to move their research elsewhere. “Without the ability to test outdoors in the United States soon, we will have no choice but to divert even more of our research and development resources abroad.”

Amazon drones are currently being tested in Cambridge, England, and the company continues transferring their research to the UK location due to the strict U.S. regulations.

In the UK, experimental flights don’t require a special license. 300 licenses have already been issued for commercial drone use.

Amazon’s drone delivery service will be called Prime Air, and while the company continues their research, CEO, Jeff Bezos, says it could be half a decade before the program officially launches.

U.S. e-commerce sales are expected to be $500 billion in 2018, a little over $200 billion than what it was in 2013. Delivery services will be put to the test with this increase. Already, Amazon is trying to create better delivery options. Just recently, the company announced their new program that would get packages to a buyer’s address within an hour, using bicycle messengers. As of now, the program will only be available in Manhattan.

If Bezos meets his optimistic deadline, Amazon drones will be available near 2018, when the Prime Air program could have a very high demand.

It all depends on how things play out between them and the FAA.

If you’re wondering how Amazon Drones will work, here is their promo video.