Editor's note: David Gergen is a senior political analyst for CNN and has been an adviser to four presidents. A graduate of Harvard Law School, he is a professor of public service and director of the Center for Public Leadership at Harvard University's Kennedy School of Government. Follow him on Twitter at @david_gergen. Daniel Katz, his research assistant, is a graduate of Brandeis University.The opinions expressed in this commentary are solely those of the authors.
(CNN) -- "How did it all begin?"
Exactly a year after the Cuban Missile Crisis, President John F. Kennedy stood before students and recalled how in 1914, Prince Bulow of Germany asked that question of the German Chancellor as Europe slid into a catastrophic world war. The chancellor wearily replied, "Ah, if one only knew."
Today, as we watch the fracturing of Iraq, we would be wise to ask a different question: "How does one end a war?" The answer remains elusive, but Iraq is quickly becoming a case study in how not to do it. And unless we learn from this experience, Afghanistan could well be next.
Unfortunately, as Gideon Rose shows in his 2010 book, "How Wars End," this is not the first time we've fumbled the end of a war. He argues that the U.S. has often gone wrong because it failed to leave a sustainable postwar structure in place, citing the Treaty of Versailles after World War I, a prolonged conflict and then stalemate in Korea, the chaos in Vietnam, and so on.
In this case, the administration that launched the Iraq war deserves the lion's share of blame for how badly it has gone. A case can be made that former President George W. Bush's team was misled by faulty intelligence on weapons of mass destruction, but they were the ones who made the wrong calls on going in with too few troops and then disbanding the Iraqi army, turning the country into a cauldron of sectarian hatreds and violence.
But after the 2007 troop surge, the Bush team could also make a credible argument they left an Iraq that was fairly stable and had a decent chance at self-governance. President Barack Obama himself proclaimed in 2011 as he withdrew the last American troops, "We're leaving behind a sovereign, stable and self-reliant Iraq."
So how did Iraq then tumble into a civil war? How come no top official in Washington saw it coming or appreciated how quickly Sunni jihadists would seize control of a third of the country? Could the U.S. have prevented the breakup?
Speaking with military and national security leaders who have retired in the past few years, one finds a unanimous view that Iraqi Prime Minister Nouri al-Maliki was the one who blew it since American troops left him fully in charge. Forcing Sunnis and Kurds out of power, establishing an authoritarian, corrupt and often brutal Shia regime, and filling the ranks of his American trained army with cronies and incompetents, al-Maliki invited a rebellion. That's why recent U.S. military leaders think al-Maliki has to go -- immediately!
But these same leaders believe there was a chance -- no guarantees but a chance -- that if the United States had left behind a strong residual force under a status-of-forces agreement, the current disaster might have been avoided.
For one thing, a U.S. force on the ground would have sent a clear signal to insurgents not to mess with things. For another, the U.S. would have kept better intelligence and could more easily head off trouble. Just as important, a top U.S. general, speaking for the President, would have been whispering into al-Maliki's ear. U.S. commanders over the years -- from Petraeus to Odierno -- found this direct line of communication vital to keeping al-Maliki on a reform path and away from power consolidation.
The story of why we failed to leave behind a residual force has been well told elsewhere. One of the best sources is the 2013 book "The Endgame" by Michael Gordon and Gen. Bernard Trainor. This past week, Peter Beinart provided an excellent autopsy in a piece for The Atlantic. Beinart's is the more surprising as he attacks the Obama administration from a liberal vantage point.
Gordon and Trainor report that Obama's top military leadership -- Joint Chiefs Chairman Adm. Michael Mullen, Defense Secretary Robert Gates and others -- wanted to keep a residual force and thought anything less than 16,000 troops would be insufficient. But they ran into resistance on two fronts. The Prime Minister wanted Americans out; al-Maliki had designs of his own for the exercise of power. The Obama White House has long argued that it was al-Maliki who scuppered any deal.
As accounts like those of Gordon and Trainor along with Beinart have shown, however, the White House was always half-hearted about pushing. The President was skeptical of his military advisers and apparently sympathetic to political advisers who wanted to get out of Iraq pronto -- and certainly before the 2012 elections. So, Obama overruled recommendations from his military leaders and presented the Iraqis with a plan for 3,500 continuous troops. Squabbles broke out between both sides and eventually an agreement fell apart.
If Obama was unhappy, he had a strange way of showing it. In the run-up to elections in 2012, he traversed the campaign trail celebrating the fulfillment of his promise to pull every last troop out of Iraq.
We will never know for sure whether a residual American force would have saved Iraq as a sovereign, stable nation -- what it seemed when we left. Sectarian hatreds there run back centuries, and ultimately they must take responsibility for their own destinies. We can't save people who won't save themselves.
But it would not be surprising if in his next edition, Gideon Rose adds to his chapter on Iraq and repeats his argument that America's wars have often ended badly when we fail to put in place a sustainable postwar structure before we leave.
The looming question is whether we will now make the same mistake in Afghanistan. After all, the President has now declared that all American troops will be out of there in 2016 -- just by coincidence, of course, the same year as the next presidential election.