The Pentagon's secretive X-37B spaceplane landed in Florida on Sunday after a record-long orbital flight lasting more than two years, the U.S. Air Force said, capping the latest test mission for an array of military technologies.

The unpiloted X-37B, built by Boeing Co., touched down on an air strip at NASA's Kennedy Space Center at 3:51 a.m. ET after spending 780 days orbiting Earth as the Air Force's fifth flight mission under the Orbital Test Vehicle program, the Air Force said.

The spaceplane, roughly the size of a small bus and sharing many design features with NASA's Space Shuttle, was sent into orbit in 2017 atop a SpaceX Falcon 9 rocket, embarking on a mission managed by the Washington-based Air Force Rapid Capabilities Office to conduct various classified technology experiments in a long-duration space environment.

"The X-37B continues to demonstrate the importance of a reusable spaceplane," Barbara Barrett, the newly appointed Air Force secretary, said in a statement. "Each successive mission advances our nation's space capabilities."

The previous X-37B mission lasted 718 days and landed in 2017. Sunday morning's landing tallies 2,865 total days for the program overall, the Air Force said.

The Pentagon, increasingly reliant on space technologies, recently created the U.S. Space Command and is asking Congress to approve funding for a proposed Space Force, which would serve as a new branch of the military.

"The sky is no longer the limit for the Air Force and, if Congress approves, the U.S. Space Force," General David L. Goldfein, Chief of Staff of the Air Force, said.