The debate over whether to continue production of the F-22 Raptor has been one of the most politically charged and controversial budget issues in recent memory, spawning lobbying efforts that include contractor-sponsored newspaper ads and letter-writing campaigns.

The F-22 is, unquestionably, the most capable fighter in our military inventory. Its advantages include stealth and speed; while optimized for air-to-air combat, it also has a ground attack capability.

We assessed the issue from many angles, taking into account competing strategic priorities and complementary programs and alternatives -- all balanced within the context of available resources.

We are often asked: How many F-22s does the Air Force need? The answer, of course, depends on what we are being asked to do. When the program began, late in the Cold War, it was estimated that 740 would be needed. Since then, the Defense Department has constantly reassessed how many major combat operations we might be challenged to conduct, where such conflicts might arise, whether or how much they might overlap, what are the strategies and capabilities of potential opponents, and U.S. objectives.

These assessments have concluded that, over time, a progressively more sophisticated mix of aircraft, weapons and networking capabilities will enable us to produce needed combat power with fewer platforms. As requirements for fighter inventories have declined and F-22 program costs have risen, the department imposed a funding cap and in December 2004 approved a program of 183 aircraft.

Based on different warfighting assumptions, the Air Force previously drew a different conclusion: that 381 aircraft would be required for a low-risk force of F-22s. We revisited this conclusion after arriving in office last summer and concluded that 243 aircraft would be a moderate-risk force. Since then, additional factors have arisen.

First, based on warfighting experience over the past several years and judgments about future threats, the Defense Department is revisiting the scenarios on which the Air Force based its assessment. Second, purchasing an additional 60 aircraft to get to a total number of 243 would create an unfunded $13 billion bill just as defense budgets are becoming more constrained.

This decision has increasingly become a zero-sum game. Within a fixed Air Force and overall Defense Department budget, our challenge is to decide among many competing needs. Buying more F-22s means doing less of something else. In addition to air superiority, the Air Force provides a number of other capabilities critical to joint operations for which joint warfighters have increasing needs. These include intelligence, surveillance and reconnaissance, command and control, and related needs in the space and cyber domains. We are also repairing years of institutional neglect of our nuclear forces, rebuilding the acquisition workforce, and taking steps to improve Air Force capabilities for irregular warfare.

It was also prudent to consider future F-22 procurement during the broader review of President Obama's fiscal 2010 defense budget, rather than as an isolated decision. During this review, we assessed both the Air Force and Defense Department's broader road maps for tactical air forces, specifically the relationship between the F-22 and the multi-role F-35 Joint Strike Fighter, which is in the early stages of production.

The F-22 and F-35 will work together in the coming years. Each is optimized for its respective air-to-air and air-to-ground role, but both have multi-role capability, and future upgrades to the F-22 fleet are already planned. We considered whether F-22 production should be extended as insurance while the F-35 program grows to full production. Analysis showed that overlapping F-22 and F-35 production would not only be expensive but that while the F-35 may still experience some growing pains, there is little risk of a catastrophic failure in its production line.

Much rides on the F-35's success, and it is critical to keep the Joint Strike Fighter on schedule and on cost. This is the time to make the transition from F-22 to F-35 production. Within the next few years, we will begin work on the sixth-generation capabilities necessary for future air dominance.

We support the final four F-22s proposed in the fiscal 2009 supplemental request, as this will aid the long-term viability of the F-22 fleet. But the time has come to close out production. That is why we do not recommend that F-22s be included in the fiscal 2010 defense budget.

Make no mistake: Air dominance remains an essential capability for joint warfighting. The F-22 is a vital tool in the military's arsenal and will remain in our inventory for decades to come. But the time has come to move on.

Michael Donley is secretary of the Air Force. Gen. Norton Schwartz is chief of staff of the Air Force.