President Barack Obama, saying it is time to "turn the page" on the U.S. mission in Afghanistan, announced Tuesday that the comparatively small advisory force of 9,800 U.S. military personnel expected to remain in that war-torn country when American combat forces leave this year will also be withdrawn by the end of 2016.

But wars are not novels. Professional assessments by NATO and U.S. experts conclude that the Afghan war will intensify in coming years, and the Afghanistan National Security Forces's (ANSF) need for foreign military support will require a much longer commitment if it is to hold the Taliban at bay and prevent a resurgence of al-Qaida.

In theory President Obama could try to arrange a further commitment of U.S. forces beyond 2016 if the outlook remains as grim as these studies forecast. But his evident distaste for the Afghan engagement makes such a turnaround unlikely. As important, the president's decision will diminish if not kill plans for Afghan support by other NATO members. And that could cripple the prospects for a negotiated settlement of the Afghan civil war.

The last time the Taliban ruled Afghanistan they gave al-Qaida the operating base it used to plan the 9/11 attacks on the United States. They employed terror to control the population, and they virtually eliminated women's rights and education during their reign.

The most recent expert assessment, provided to Congress in January by the Department of Defense, was performed by CNA Corporation, a non-profit research and analysis organization analogous to the RAND Corporation.

The assessment is likely to reflect the best judgment of the U.S. military.

The study group included several retired high-ranking officers, including former U.S. Army Chief of Staff Gen. Peter Schoomaker, who also served as commander of the U.S. Special Operations Command, and Lt. Gen. Francis Kearney III, a former deputy commander of Special Operations.

They found that the Taliban and its ally, the Pakistan-supported Haqqani militia, "will become a greater threat to Afghanistan's stability in the 2015-2018 timeframe than it is now," and that because of serious shortcomings in the Afghan government's ability to support its own armed forces, "international enabler support - to include advisors - will be essential to ANSF success through at least 2018."

Given such outside support a stronger and better organized Afghan security force could prevent a Taliban victory and "a negotiated political settlement to end the war would become much more likely in the 2019-2023 timeframe."

The costs of providing foreign military assistance and advice to Afghanistan over this extended period would be a small fraction of what the Obama administration has spent on the war, which it enlarged upon taking office in 2009.

The presence of 9,800 U.S. military advisors in Afghanistan is not the same as having 100,000 troops there as the U.S. did at the peak of President Obama's "surge" strategy.

The president's ill-advised announcement of an exit timetable needlessly gives the Taliban an advantage - and undermines the crucial, ongoing task of preventing Afghanistan from reverting into an al-Qaida haven.