The Pentagon’s “black budget”—the money spent on programs and activities that are unacknowledged in nonclassified documents—amounts to around $68 billion in fiscal 2017, according to an Aviation Week analysis. This is about 12% of the total $582 billion budget and is similar in magnitude to the entire defense budgets of France, Russia or the U.K., as estimated by the International Institute for Strategic Studies and the Stockholm International Peace Research Institute. 
Classified budgets are separate line items spread throughout R&D, procurement, and operations and maintenance subbudgets. The total amounts are similar—$22.5 billion in R&D, $20.7 billion in procurement and $24.9 billion in operations—but represent different percentages of those accounts. Almost one-third of R&D and nearly 19% of procurement are classified, but only 10% of procurement costs are. The black-world share of acquisition (R&D and procurement) is 24%, versus 17% at the end of the Cold War. 
Pictured after a record-setting mission in 2014, the Boeing X-37B is an example of “gray-black” programs run by the Air Force but likely supported by intelligence budgets. Credit: U.S. Air Force

The secret programs and activities do not include the B-21 Long-Range Strike Bomber (LRS-B) or the Long-Range Standoff missile, the replacement for the Air-Launched Cruise Missile. Although programmatic and technical details of these projects are secret, their existence is acknowledged and their budgets are listed openly. 
One widely reported black program is the Northrop Grumman RQ-180 intelligence, surveillance and reconnaissance (ISR) UAV, funded under Air Force R&D and procurement accounts. A long-running Air Force procurement line item, listed under “missile procurement,” is considered to fund the production of imaging satellites and signals intelligence spacecraft for the National Reconnaissance Office (NRO). It amounts to $1.06 billion in the budget. There are other, smaller, Air Force programs that cannot be found in the unclassified budget: One of them, the General Atomics-Aeronautical Systems Predator C/Avenger UAV, is known to be in service. 
The largest classified line item is in Air Force “other procurement,” which covers everything from small-arms ammunition to ISR ground systems and was previously identified as “selected activities.” The 2017 amount is $18.6 billion. 
After that, the second-biggest secret item is $15.7 billion, for defensewide classified programs in the operations and maintenance budget. Those two items account for half the classified budget, and both are several times larger than almost any other line item. 
The Air Force service has always had the largest share of the black budget. Its classified R&D is twice that of the Army and Navy combined—their Army and Navy classified procurement is under $20 million.
However, this reflects a major complicating factor in the analysis of the black budget: It has been generally accepted for years that the major elements of the intelligence community (IC)—the CIA, National Security Agency and NRO—are chiefly funded by the Air Force. Indeed, the service has in recent years been given approval to talk about its “blue” and “nonblue” budgets, the latter being money passed directly to the IC. Most of the difference between blue and nonblue is in procurement ($21.5 billion) and R&D ($8.5 billion), according to 2017 budget documents. 
But the nonblue R&D is still $4.6 billion less than the Air Force lists in classified R&D, indicating that the service has major R&D programs that are not pass-throughs to the IC. To confuse the picture further, many major IC projects—including the design, development and support of NRO spacecraft—are Air Force-type activities. Other programs of this type are the manned and unmanned ISR aircraft owned by the CIA but developed, procured and operated by Air Force personnel. This pattern has existed for more than 60 years. It continues with the CIA’s force of MQ-9 Reaper UAVs and possibly the Predator C systems. The RQ-170 Sentinel and RQ-180 UAVs are also likely to be funded, at least in part, from the “nonblue” budget. 
Other clues to the direction of the classified budget are the existence of at least two “black-to-gray” offices in the Pentagon. The Air Force’s Rapid Capabilities Office (RCO), formed in April 2003, ran the RQ-170 and X-37B programs and, most likely, the RQ-180; it was selected to run the B-21 bomber program. 
The RCO pattern was used by Defense Secretary Ash Carter to establish the Strategic Capabilities Office (SCO), formed in 2012 to accomplish “rapid innovation by building on what we have,” he has said. SCO is the home of the “arsenal plane . . . based on one of our oldest platforms,” which will operate in conjunction with Lockheed Martin F-22s and F-35s and “act as a very large magazine.” SCO is also running a demonstration of a hypervelocity projectile fired from Navy and Army large-caliber guns—but it is likely to be the home of classified programs.