Almost a decade after the United States military launched a massive operation to clear the militants out of Fallujah, Al Qaeda’s black flag is once again flying over the city and security forces are preparing for yet another large-scale offensive to retake the city. The event is a momentous one, but one that needs to be kept in perspective. Unlike some have argued, the second fall of Fallujah is not analogous to the fall of Saigon. Al Qaeda is not the Viet Cong, much less the North Vietnamese Army. While Al Qaeda can spark sectarian violence, they lack the military power, the outside backing, or the internal support to seize control of Iraq—like the Communist forces did in South Vietnam just shy of four decades ago. Still, Al Qaeda’s dramatic resurgence—and more broadly the return of sectarian violence—only two years after American forces left Iraq must give us pause and prompt a reassessment of American policy.

First, this rise in violence should inform our understanding of the past. By all accounts, the 2007 Iraq Surge was a stunning success: within a year of its execution, all major violence indicators fell between 40 to 80 percent and civilian deaths declined by 82 percent from their peak in November 2006. And yet,the Surge was not about winning “hearts and minds” or fundamentally shifting Iraq’s internal dynamics. Indeed, if polling is any indicator, the United States never won the heart or the mind of the average Iraqi. Long after violence declined, a February 2009 ABC News, BBC and NHK poll found that 73 percent of Iraqis had “not very much” or no confidence in American forces, while 69 percent thought that American forces had done “quite a bad” or a “very bad” job in Iraq.

Rather, the Surge worked because the United States took control of Iraq’s disparate factions. Sometimes, control was literal and physical: concrete walls and checkpoints emplaced along sectarian fault lines. Other times, control assumed a more subtle form, such as when the United States successfully leveraged Sunni fears of Al Qaeda and angst of over an increasingly powerful Shiite government into the Awakening or the creation of the Sons of Iraq. These militias—often recruited from former Sunni insurgents—entered into a marriage of convenience with the Coalition to fight against Al Qaeda in the short term and help secure the future of the Sunni population in the long run. Together, these policies produced a stunning reversal of fortunes.

This formula, however, has its downsides. Physical control only reduces violence insofar as checkpoints are manned and walls remain in place. More importantly, continued peace depended on a powerful American presence playing honest broker between the Sunni militias and the Shiite government. And so, as the United States left, violence returned. Add to this the spillover effects from the Syrian civil war, and Iraq now seems poised on the brink of a full-fledged civil war. As General David Petraeus concluded in his recent Foreign Policypiece, “Iraq today looks tragically similar to the Iraq of 2006, complete with increasing numbers of horrific, indiscriminate attacks by Iraq's Al Qaeda affiliate and its network of extremists.”

The implications then for current American policy are grim. Now, well over a dozen years into the War on Terrorism, the United States has perfected the art of man-hunting. Thanks to technological advances—perhaps most notably with unmanned aerial vehicles—and the hard work of the intelligence and special operations communities, the United States has demonstrated that it can successfully target terrorist organizations’ senior leadership. Should such an effort be made in Iraq, it could neutralize some of the nastier elements in the country. Similarly, more indirect efforts—like supplying Iraqi Security Forces with equipment or aiding them with intelligence—would also help blunt Al Qaeda’s resurgence.

And yet, neither military aid nor special-operations missions will likely fully stave off the turmoil. Keeping Iraq’s sectarian tensions in check requires a powerful, independent guarantor and for the United States—or any other party for that matter—successfully play this role, in turn, requires a much larger force commitment than the Obama administration, the American public or the world at large seems to have the stomach for at the moment. And so, Iraq’s future today remains bleak.

In the end then, the Iraq War and its bloody aftermath teaches two broader lessons for future policymakers. First, counterinsurgencies, especially in this day and age, are hard to win and consequently, should be avoided at all costs. That said, once there is progress in these conflicts, policymakers should be equally wary of a rush to exit. Gains in these wars are fragile and without continued involvement, they often prove ephemeral. And so while the fall of Fallujah may not be akin to the fall of Saigon, the moral of the story may be the same: while we often focus on the costs of staying in places like Iraq, there is also a price to be paid for retreat, and those costs can be quite high indeed.

Raphael S. Cohen is a predoctoral fellow in Foreign Policy at the Brookings Institution and Ph.D. candidate in Government at Georgetown University. He served in Iraq as a United States Army officer from 2005-2006 and again from 2007-2008.