The U.S. Air Force’s fleet of drones is being strained to the “breaking point,” according to senior military officials and an internal service memo acquired by The Daily Beast. And it’s happening right when the unmanned aircraft are most needed to fight ISIS.

The Air Force has enough MQ-1 Predator and MQ-9 Reaper drones. It just doesn’t have the manpower to operate those machines. The Air Force’s situation is so dire that Air Combat Command (ACC), which trains and equips the service’s combat forces, is balking at filling the Pentagon’s ever increasing demands for more drone flights.

“ACC believes we are about to see a perfect storm of increased COCOM [Combatant Commander] demand, accession reductions, and outflow increases that will damage the readiness and combat capability of the MQ-1/9 enterprise for years to come,” reads an internal Air Force memo from ACC commander Gen. Herbert “Hawk” Carlisle, addressed to Air Force Chief of Staff Gen. Mark Welsh. “I am extremely concerned.”

“ACC will continue to non-concur to increased tasking beyond our FY15 [fiscal year 2015] force offering and respectfully requests your support in ensuring the combat viability of the MQ-1/9 platform,” Carlisle added.

In other words, the Air Force is saying that its drone force has been stretched to its limits. “It’s at the breaking point, and has been for a long time,” a senior service official told The Daily Beast. “What’s different now is that the band-aid fixes are no longer working.”

In the internal memo, Carlisle noted that the Air Force’s current manning problem is so acute that the service will have to beg the Pentagon to reconsider its demand for 65 drone combat air patrols, or CAPs, as early as April 2015. (Each CAP, also known as an “orbit,” consists on four aircraft.)

But senior military leaders in the Pentagon have been pushing back hard against any reduction in the number of drone orbits, particularly as demand has surged in recent months over Iraq and Syria because of the war against ISIS. In fact, the Pentagon is so fervent in its demand for more Predator and Reaper patrols that the top military brass made an end run to bypass regular channels to increase the number of drone orbits, the ACC alleges.

“The reduced offering of 62 CAPs (plus a 60-day Global Response Force) has been submitted to the Joint Staff; however, the Joint Staff has indicated their desire to circumvent normal processes while proposing their own offering of 65 MQ-1/9 CAPs,” Carlisle wrote. “This simply is not an option for ACC to source indeterminately.”

Carlisle writes that the Air Force would want a crew ratio of 10 to one for each drone orbit during normal everyday operations. During an emergency that ratio could be allowed to drop to 8.5 people per orbit. However, the Air Force is so strapped for people that the ratio has dropped below even that reduced level.

“ACC squadrons are currently executing steady-state, day-to-day operations (65 CAPs) at less than an 8:1 crew-to-CAP ratio. This directly violates our red line for RPA [remotely pilot aircraft] manning and combat operations,” Carlisle wrote. “The ever-present demand has resulted in increased launch and recovery taskings and increased overhead for LNO [liaison officer] support.”

The Air Force has been forced to raid its schools for drone operators to man the operational squadrons that are flying combat missions over places like Iraq and Syria. As a result, training squadrons—called Formal Training Units (FTU)—are being staffed with less than half the people they need. Even the Air Force’s elite Weapons School—the service’s much more extensive and in-depth version of the Navy’s famous Top Gun school—course for drone pilots was suspended in an effort to train new rookie operators.

Overworked drone crews have had their leaves canceled and suffered damage to their careers because they could not attend required professional military education courses.

The result is that drone operators are leaving the Air Force in droves. “Pilot production has been decimated to match the steady demand placed upon the RPA community by keeping ‘all hands’ in the fight,” Carlisle wrote. “Long-term effects of this continued OPSTEMPO are manifested in declining retention among MQ-1/9 pilots, FTU manning at less than 50%, and enterprise-wide pilot manning hovering at about 84%.”

The Air Force has about seven pilots for every eight drone pilot slots, in other words.

But it takes more than just pilots to operate the drone fleet. In addition to the pilots who “fly” the MQ-1s and MQ-9s, there are sensor operators who work the cameras and other intelligence-gathering hardware onboard the unmanned aircraft. Further, there are maintenance crews who have to fix those drones. Perhaps most crucially, drones require hundreds of intelligence analysts who have to comb through thousands of hours of video surveillance footage to understand what the flight crews are watching.

“Some have looked at this as a problem with just RPA pilots and the number of them required for these CAPs, but that ignores the tail required for supporting RPA operations,” a senior Air Force official said. “This tail requires hundreds of man-hours to support every hour of flight in forward operations, maintenance, and most starkly in the processing, exploitation, and dissemination of the intelligence that RPAs create.”

The problem for Carlisle and the Air Force is that even as the demand increases on the drone fleet, fewer new troops enter the ranks while more and more veteran operators vote with their feet.