The CIA used a new futuristic tool called “Ghost Murmur” to locate and rescue a second American pilot who had been shot down in southern Iran, The New York Post reports.

According to the outlet, the secret technology is based on long-range quantum magnetometry to detect the electromagnetic signature of a human heartbeat and combines it with artificial intelligence software to distinguish the signal from background noise.

This marked the first field use of the tool by the intelligence agency. On Monday afternoon, U.S. President Donald Trump and CIA Director John Ratcliffe mentioned it during a briefing at the White House.

“It’s like hearing a voice in a stadium, except the stadium is a thousand-square-mile desert,” a source familiar with the program told the publication. “Under the right conditions, if your heart is beating, we will find you.”

Sources familiar with Lockheed Martin’s intelligence-gathering technologies said that “Ghost Murmur” was developed by Skunk Works, the aerospace giant’s secret advanced development division.

According to another source, the technology was successfully tested on Black Hawk helicopters for potential future use on F-35 fighter jets.

The missing and wounded weapons systems officer had been hiding in a mountain crevice after his F-15 aircraft was shot down late last week. He survived for two days in desert terrain while Iranian forces searched the area, reportedly offering a reward for his capture.

According to a source, the relatively empty desert landscape was ideal for the first operational use of “Ghost Murmur.”

“The name is intentional. ‘Murmur’ is a clinical term referring to a heartbeat rhythm. ‘Ghost’ implies searching for someone who has practically disappeared. This was the cleanest environment imaginable due to low electromagnetic interference, almost no competing human signatures, and at night, the thermal contrast between a living body and the desert surface, giving operators an additional layer of confirmation,” the source explained.