A Pentagon agency’s attempts to field an unmanned aircraft capable of traveling anywhere in the world in less than an hour were dealt another setback on Thursday, as officials lost contact with the vehicle during a highly anticipated test flight.

For years, the Defense Advanced Research Projects Agency has tried to develop an aircraft capable of traveling about 13,000 miles per hour — a flight speed that would have it rocket from New York to Los Angeles in about 12 minutes. The project has been part of the Pentagon’s efforts to build a “prompt global strike” capability, allowing the military to quickly eliminate threats worldwide.

But a year after officials lost contact with the Falcon Hypersonic Technology Vehicle 2, history seemed to be repeating itself on Thursday.

The plan had been to launch the aircraft from an Air Force base in California, have it separate from a rocket in the upper atmosphere and then have it come barreling through the sky. At the end of its test flight, the arrowhead-shaped aircraft would plunge into the ocean.

But on Thursday, DARPA said in a statement that it had collected only about nine minutes of data from the Falcon before an “anomaly caused loss of signal.” Initial indications were that the aircraft had “impacted the Pacific Ocean along the planned flight path.”

“We know how to boost the aircraft to near space. We know how to insert the aircraft into atmospheric hypersonic flight. We do not yet know how to achieve the desired control during the aerodynamic phase of flight,” said Air Force Maj. Chris Schulz, the program manager for the Falcon. “It’s vexing; I’m confident there is a solution. We have to find it.”

He added: “As today’s flight indicates, high-Mach flight in the atmosphere is virtually uncharted territory.”

A team of experts is expected to analyze the flight data to determine what went wrong.

DARPA says surface temperatures on the Falcon were expected to exceed 3,500 degrees Fahrenheit, hot enough to melt steel. It was supposed to fly about 22 times faster than a commercial airliner.