Amazon has agreed to lease 20 Boeing 767 freighter aircraft from Air Transport Services Group (ATSG), the company announced Wednesday. The announcement confirms rumors that began circulating in December that Amazon was looking to lease large cargo jets.

“Since last summer, we have been working closely with Amazon to demonstrate that a dedicated, fully customized air cargo network can be a strong supplement to existing transportation and distribution resources,” said Joe Hete, President and CEO of the American aircraft leasing and air-cargo transportation company, in a statement. “We are excited to serve Amazon customers by providing additional air cargo capacity and logistics support to ensure great shipping speeds for customers.”

Dave Clark, Amazon senior vice president of worldwide operations and customer service, said in a news release that the company is “excited to supplement our existing delivery network with a great new provider, ATSG, by adding 20 planes to ensure air cargo capacity to support one and two-day delivery for customers.”

Amazon has been expanding its delivery infrastructure as it seeks to reduce shipping costs, and speed up delivery to customers. Some observers have speculated that Amazon intends to compete with UPS and other shipping services. Amazon executives, however have tried to dispel the idea, saying they only wish to supplement existing delivery channels.

But the company’s moves suggest management is more ambitious than they’re letting on. In addition to enlisting jets, Amazon has also experimented with package-delivering drones. The retailer is reportedly in negotiations to buy a 100-percent stake of the No. 2 package delivery service in France, and is building a package-locker service in Europe.

Amazon is also testing an Uber-esque home delivery service, called Amazon Flex, using private drivers to deliver packages to customers’ doors.

At minimum, Amazon wants to reduce the cost of shipping goods. In January, the web’s top retailer reported that net-shipping costs reached an all-time high of $1.85 billion during the fourth quarter of 2015, and surpassed $5 billion for the full year.