A recent glimpse at the future of robotic warfare proves tank robots aren't ready for the battlefield just yet—but soldiers are enthusiastic about tiny drones that can be mistaken for birds.

Unites States soldiers based in Hawaii spent half of last month testing out cutting-edge robotic prototypes in exercises as a part of Pacific Manned-Unmanned Initiative (PACMAN-I). Members of the 25th Infantry Division controlled air and land drones to determine what technology could actually benefit soldiers. It was the third time in history human that soldiers have collaborated with robot counterparts in a simulated war zone.

Secretary of the Army Eric Fanning visited the exercise on July 26, a sign of the interest the Army is taking in the battlefield applications of unmanned vehicles. "We need to be making sure we're fielding new technology as quickly as we can," Fanning said, in a statement. "It doesn't do any good if we're just investing in great technology if we don't actually get it into the field for soldiers."

The Department of Defense (DoD) spends billions of dollars developing combat technology every year. But all that R&D can be scrapped in an instant if the people who are supposed to use the machines deem them unfit for battle. Last year, after the DoD spent $32 million on the Boston Dynamic-developed Legged Squad Support System, the was robotic pack mule was put to pasture because senior Marine officials thought it was too noisy.