Americans paused recently to remember the tenth anniversary of 9/11. In years ahead they will remember and debate the wisdom of American policy and actions in Afghanistan. Far fewer will reflect on the significance of 10/7/2001; the date marking the start of Operation Enduring Freedom (OEF)-the U.S. and coalition attacks to wipe out Al Qaeda.

The opening phase of OEF exemplified a military culture of flexibility and a broad appreciation for operational economy. The measured application of modern airpower, in conjunction with a light footprint of special operations and other government agency personnel on the ground acting as intelligence, surveillance, and reconnaissance (ISR) sensors, partnering with the Afghan Northern Alliance, achieved what the Northern Alliance had not been able to accomplish for five years — removal of the Taliban regime.

Removing the Taliban was one of three critical objectives directly affecting U.S. security — the other two were the installation of a regime in Afghanistan friendly to U.S. security interests, and elimination of Al Qaeda’s terrorist training camps. In three short months these objectives were achieved. So the trillion dollar question is: why did we then pour hundreds of thousands of ground forces into Afghanistan over the next decade after these vital security objectives were realized? This is not simply a question of historical interest. The answer illustrates the importance of clearly defining U.S. security objectives, and acting rapidly and effectively with just the right amount of force to achieve them.

Neutering Al Qaeda, and eliminating Afghanistan as Al Qaeda’s sanctuary were critical U.S. security objectives. Turning Afghanistan into a modern Jeffersonian Democracy was and is not. Critics may insist that early 2002 was too soon to recognize that Al Qaeda in Afghanistan had been neutered, but when we shifted from a strategy of counterterrorism to one of counterinsurgency we shifted from a set of strategic objectives that were vital to the U.S. to a set of objectives that were not.

This shift occurred gradually and without fanfare — with the exception of the publicly celebrated “surges” of additional forces-resulting in a serious case of mission creep. We evolved from a mission of unquestionable security rationale into one that was not ours to solve; namely, the transfiguration of the tribal peoples of Afghanistan into citizens of a modern nation-state. This mission creep will not be easy to admit, but it is necessary to recognize to avoid similar outcomes in the future.

As we reflect on a decade of conflict in Afghanistan and come to terms with the reality that we must adjust our defense posture in an era of fiscal austerity, we cannot afford to simply salami slice our forces to meet arbitrary dollar targets. We must choose between national security goals that are vital and goals that are simply desirable, design a prudent strategy to succeed in achieving vital goals, construct an effective force mix to attain them, and once attained, have the wisdom to move on.

Retired Gen. David Deptula was director of the Combined Air Operations Center for OEF in 2001. He is now a consultant and a member of the AOL Board of Contributors.