Air Force leaders are saying the military may already have enough unmanned aircraft systems to wage the wars of the future. And the Pentagon's shift to Asia will require a new mix of drones and other aircraft because countries in that region are better able to detect unmanned versions and shoot them down.

If the Pentagon does slow the huge building and deployment program, which was ordered several years ago by then-Defense Secretary Robert Gates, it won't affect the CIA drone strikes in Pakistan, Yemen and elsewhere against terror suspects. Those strikes were brought center stage last week during the confirmation hearing for White House counterterror chief John Brennan, President Obama's pick to lead the CIA.

Gen. Mike Hostage, commander of Air Combat Command, said senior leaders are analyzing the military's drone needs and discussions are beginning. But he said the current number patrolling the skies overseas may already be more than the service can afford to maintain.

Overall, Pentagon spending on unmanned aircraft has jumped from $284 million in 2000 to nearly $4 billion in the past fiscal year, while the number of drones owned by the Pentagon has rocketed from less than 200 in 2002 to at least 7,500 now. The bulk of those drones are small, shoulder-launched Ravens owned by the Army.

The discussions may trigger heated debate because drones have become so important to the military. They can provide 24-hour patrols over hotspots, gather intelligence by pulling in millions of terabytes of data and hours of video feeds, and they can also launch precisely targeted airstrikes without putting a U.S. pilot at risk.

The analysis began before Brennan's confirmation hearings, where he was questioned sharply about the CIA's use of drones to kill terror suspects, including American citizens overseas. The CIA has its own fleet of drones that it uses on its counterterror missions, and any decision to stop building drones would be unlikely to have any effect on that program.

The Air Force discussions are focused more on whether the military's drone fleet is the right size and composition for future conflicts.

There has been a seemingly insatiable appetite within the military for the unmanned hunter/killers, particularly among top combat commanders around the world who have been clamoring for the drones but have seen most resources go to the wars in Iraq and Afghanistan.

"We are trying to do the analysis and engage in the discussion to say at some point the downturn in operations and the upsurge in capabilities has got to meet," Hostage said.

Hostage, interviewed in his office at Langley Air Force Base in Hampton, Va., amid the intermittent roar of fighter jets overhead, said the military's new focus on the Asia-Pacific region will require a different mix of drones and other aircraft. Unlike in Afghanistan, where the U.S. can operate largely without fear of the drones being shot down, a number of countries in the Pacific could face off against American aircraft -- either manned or unmanned.

Right now, Predator and Reaper drones that pilots fly remotely from thousands of miles away are completing 59 24-hour combat air patrols a day, mostly in Afghanistan, Pakistan and areas around Yemen and the Africa coast. The standing order is for the Air Force to increase that number of air patrols to 65 a day by May 2014, although officials say that is an arbitrary number not based on an analysis of future combat requirements.

The staffing demands for that increase have put a strain on the Air Force, as they would require nearly 1,700 drone pilots and 1,200 sensor operators. Currently there are fewer than 1,400 pilots and about 950 sensor operators.

Lt. Gen. Larry D. James, the Air Force deputy chief of staff for intelligence, said no recommendations for changes to the projected drone fleet have been sent yet to Pentagon leaders. A key part of the decision will involve what types of drones and other aircraft will be needed as the military focuses greater concentration on the Pacific.

While Predators and Reapers have logged more than 1 million hours of combat patrols in the skies over Afghanistan and Iraq, where insurgents don't have the ability to shoot them down, they would be likely to face challenges in the more contested airspace over the Pacific.

Countries with significant air power or the ability to shoot down aircraft are scattered across the region, including China, Russia and North Korea -- as well as key U.S. allies such as Japan and Australia. America's pivot to the Pacific reflects a growing strategic concern over China's rise as a military power, amid simmering disputes over Taiwan and contested islands in the south and east China seas.

Hostage said the Predators and Reapers can be used in the Pacific region "but not in a highly contested environment. We may be able to use them on the fringes and on the edges and in small locales, but we're much more likely to lose them if somebody decides to challenge us for that space."

James said the Air Force is evaluating how much to continue to invest in drones like the Reapers that can be used for counterterrorism missions in more so-called permissive environments, versus how much investment should be shifted to other aircraft. The Air Force uses an array of aircraft, such as the U-2 spy plane, the high-altitude Global Hawk drone or satellites and systems that can gather intelligence from space.

David Deptula, a retired Air Force three-star general who was deputy chief of staff for intelligence, said the military needs to measure its drone requirements by the amount of data and intelligence needed by troops to accomplish their mission. The focus should not be on the number of drone patrols but on how well the information is being received and analyzed.

As technologies advance, he said, the Pentagon can reduce the number of drones in orbit, while still increasing the video, data and other information being transmitted.

"There are smarter ways to deliver the capabilities that are more cost effective" than just building more drones, he said.